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[MoooShuuu]

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Since I'm terrible at math I have a few questions. These are from a practice test that only gives answers and no explainations and I can't get the correct answer or I don't know how to go about answering the question!

here goes:
1)Which is largest?
23/25
27/30
15/16
14/15
7/8
*Now I know that I can get the same denominators and compare but it seems that it would take forever. Also, the cross mult way would also take long. Any tips on how to do this quickly?

2)Which line is parallel to the y-axis?
x=4y
x=(2/y)b ----> I don't understand why this is the answer.


3)A fly sits at the edge of a 12 in diameter phonograph record that is playing at 33 1/3 rev per min. Approx how fast in ft/min is the fly moving?
ans:100

4)The current sales price of a power drill is $117.00. This is $30 more than half the list price. At what discount is the drill being sold?
ans:32.8%

5)Two committees are formed with 7 people on one commitee and eight on the other. If three people are in both groups, how many people belong to only one group? ans:9

Lastly, 6) A gift of $180 is to be shared by Brett and Andrew in such a way that andrew gets 25% more than Brett. How much does Brett get?
ans: 80


Thank you all so much for the help

 

[momasboy]

So here is a suggestion for the following question...

1)Which is largest?
a) 23/25
b) 27/30
c) 15/16
d) 14/15
e) 7/8

First eliminate the obvious ones that are not the largest. If you double d) 14/15 you get 28/30, which is more than b) 27/30, so you can eliminate b). If you double e) 7/8 you get 14/16, which is less than c) 15/16, so you can eliminate e).
For each option that remains you can divide both the numerator and the denominator by the numerator. If you do that for each option you will get the following:
a) 1/1.08
b) eliminated
c) 1/1.06
d) 1/1.07
e) eliminated

The largest will now be the option with the smallest denominator, so c) is the answer. This is also kind of tedious, but if you practice your division skills and you get fast at doing this then it helps. By the way, I saw a problem like this when I took the DAT. Good luck!

-momasboy

 

[waystinthyme]

2)Which line is parallel to the y-axis?
x=4y
x=(2/y)b ----> I don't understand why this is the answer.

i would just plug in values for this one.

for x=4y

sample caculation (for x=4): x = 4y / 4 = 4y / y = 1
x: 0 / y: 0
x: 4 / y: 1

from those two values you know that the line is not parallel to the y-axis, because in order for a line to be parallel to the y-axis, the x-value must remain constant for all y-values. the y-axis is a special case, in which the x-value is 0, for all values of y.

x = (2/y)b

in this equation, b represents your y-intercept, which in this case will always be the same as our y-value (not 100% positive on this point, someone else please confirm).

again we can plug in points to find our answer.

remember: if a line is parallel to the y-axis, the x-value must remain constant for all y-values.

sample calculation (for y = 4): x = (2/y)b / x = (2/4)(4) / x = 2

y: 1 / x: 2
y: 2 / x: 2
y: 3 / x: 2
y: 4 / x: 2
y: 5 / x: 2

since our x-value remains constant for all values of y, this line is parallel to the y-axis.

-waystinthyme

 

[waystinthyme]

3)A fly sits at the edge of a 12 in diameter phonograph record that is playing at 33 1/3 rev per min. Approx how fast in ft/min is the fly moving?
ans:100

circumfrence = 2 x pi x radius = diameter x pi = 12 pi

(33 1/3 rev / minutes) x (12 pi inches / rev) x (1 ft / 12 in) = 33 1/3 pi ft / min

pi = 3.14

33 1/3 pi ft/min = 33 1/3 x 3.14 ft/min = 100 ft/min (approx.)

4)The current sales price of a power drill is $117.00. This is $30 more than half the list price. At what discount is the drill being sold?
ans:32.8%

let's represent the sales price and list price with variables...this may make it easier.

x: sale price
y: list price

117 = 1/2y + 30
87 = 1/2y
174 = y

sale price: 117
list price: 174
discount: 174-117 = 57

% discount: 57/174 = 32.8% (approx.)

-waystinthyme

 

[Marmar tala]

2) every line that is parallel to y-axis should be of this form x= a constant number

3) 12*pi~ 36 inch (the phonograph circumference)
36 * 33 1/3 = 396 inch =33 feet per min
what are other choices? I think there is something wrong in this question or I didn't get the point here 🙂

4) 117-30= 87 the half list price
87 * 2= 174 the half price
174 - 117 = 57 the discount
57 / 174 = 0.3275~ 32.8 % discount

5) one group 7 and one group 8 => 7+8=15 people but we have 3 of them in both =>15-3=12 all people => 12-3=9 people that are in only one commitee

6) a: gift for Brett => a+0.25a :Andrew's gift
180= a+a+0.25a=2.25 a => a=180/2.25=80

 

[waystinthyme]

5)Two committees are formed with 7 people on one commitee and eight on the other. If three people are in both groups, how many people belong to only one group? ans:9

committee 1: 7 people
committee 2: 8 people

3 people are in both committees

people only in committee 1: 7-3 = 4 people
people only in committee 2: 8-3 = 5 people

people only in one committee: 4+5 = 9 people.

just noticed all the others are answered above...

-waystinthyme

 

[Marmar tala]

yes , it was a calculation mistake 🙂

 

[CaydenPrice]

Hi,

I have a B.S. in Mathematics and a M.S. in Economics; I've been looking into possibly going into the healthcare arena, saw your post, and decided to respond to a couple of your questions...

4)The current sales price of a power drill is $117.00. This is $30 more than half the list price. At what discount is the drill being sold?
ans:32.8%

I would first start this problem as follows:

==> Given that the current sales price is $30 more than half the list price
117 = 30 + 0.5*(List_Price)
87 = 0.5*List_Price
List_Price = $174.00

Now that we know the List_Price, we can find the discount rate as follows:

174 * X = 117
X = 117/174
X = 0.6724
Discount Rate = 1 - X
Discount Rate = 1 - 0.672
Discount Rate = 0.328 = 32.8%


5)Two committees are formed with 7 people on one commitee and eight on the other. If three people are in both groups, how many people belong to only one group? ans:9

Given:
C1 = 7 People
C2 = 8 People
Know 3 People in Both Groups

So, the answer can be found as follows:
7 - 3 = 4
8 - 3 = 5
So,
4 + 5 = 9 (ANSWER)

Took each committee group and subtracted 3 because 3 people in each of the groups were in both of the groups; therefore, the remainder would be in only 1 group.
In C1 ==>

Lastly, 6) A gift of $180 is to be shared by Brett and Andrew in such a way that andrew gets 25% more than Brett. How much does Brett get?
ans: 80

Set up the question as follows:

Brett gets Y
Andrew gets 1.25*Y

Y + 1.25*Y = 180
2.25*Y = 180
Y = $80

So, Since Brett gets Y, Brett gets $80

Likewise,
Since Andrew gets 1.25*Y, Andrew gets $100

If any questions, I would be happy to explain how I got my results more thoroughly.

 

[supraman]

A little late there guy^

Anyone here take the DAT already...how do these problems compare to actual QR?

 

[chessxwizard]

QR was just plain... bad... lol. It went by so fast that I don't remember much from it.

 

[MoooShuuu]

You guys are awesome. It's nice to see people who are willing to share their knowledge instead of hoarding it 😀 thanks

 

[waystinthyme]

A little late there guy^

Anyone here take the DAT already...how do these problems compare to actual QR?

lol...

math on the DAT is pretty tough. i did well on my practice tests (20-22) but only managed an 18 on the exam. i think a lot of it is luck of the draw...my weakness in math is TRIG (along with probabilities), and my test was filled with it...timing is a big issue too. i didn't run out of time on any of my practice exams, but struggled to finish in time on the real exam. i would guess and mark any problem that looks like it will take a lot of time and make sure you get to all of the easy straightforward problems first...then come back to the more involved problems. guessing gives you a 25% chance of getting the problem correct, but leaving a question blank gives you a 0% chance of getting the problem correct...it's even worse when the problems you don't get to are the easy ones! and remember each problem in the section is worth the same amount, so it's better to completely work out as many as you can...

even if you are decent at math, i'd suggest spending a good amount of time on it. a good QR and RC score can greatly improve your AA and set you apart from other students applying to DS.

good luck...

-waystinthyme

 

[supraman]

lol...

math on the DAT is pretty tough. i did well on my practice tests (20-22) but only managed an 18 on the exam. i think a lot of it is luck of the draw...my weakness in math is TRIG (along with probabilities), and my test was filled with it...

even if you are decent at math, i'd suggest spending a good amount of time on it. a good QR and RC score can greatly improve your AA and set you apart from other students applying to DS.

good luck...

-waystinthyme

haha wow thats so funny because I score the same on practice tests and my weaknesses are also probability and trig... Thanks for the tip man

 

[MoooShuuu]

Speaking of trig... (Also my weakness in my weak area!)

Can someone explain how to do this:

Which of the following is equal to cos 59 degrees?

sin31
cos31
sin 59
cos(1/59)
Sin (1/50)

*Also if anyone has pointers on any other probable general trig questions, I would love to hear them!

While I'm here...I have some more math questions that give me problems. Although the book has an explanation, I'm just not getting it.


An express train leaves a station 3 hours after a freight train. The express train travels at 60 miles per hour and after 2 hours finds that it is still 20 miles behind the freight train. At what rate is the freight train traveling?


Anne has a total of $34 in nickels, dimes, and quarters. If she has 3 times as many dimes as quarters and two times as many nickels as dimes, how many dimes does she have?


Thanks!!!

 

[Streetwolf]

Since I'm terrible at math I have a few questions. These are from a practice test that only gives answers and no explainations and I can't get the correct answer or I don't know how to go about answering the question!

here goes:
1)Which is largest?
23/25
27/30
15/16
14/15
7/8
*Now I know that I can get the same denominators and compare but it seems that it would take forever. Also, the cross mult way would also take long. Any tips on how to do this quickly?

Cross multiplying is a good way to get the answer itself, once you narrow down choices. Sometimes you just CANNOT narrow down more than one answer in which case you are stuck.

First work around 1/2. See if some values are under or over. If you are looking for the lowest fraction, eliminate those above 1/2. If you want the highest, eliminate those below. Of course you can't do anything if they are all above/below.

Look for denominators that are easy to work with, or fractions you KNOW values for. If you have 3/4 listed, you know that's 0.75. If you have 10/11 with that, that's CLEARLY above 0.75. As someone pointed out here, you have 14/15 and 27/30. Since 15 goes into 30 twice, you really have 28/30 and 27/30. So 27/30 is eliminated. 7/8 and 15/16 works that way too. You can eliminate 7/8.

You are left with 15/16, 14/15, and 23/25. Which one is best? Well I'd look at 15/16 and 14/15. They are both n/n+1. Which is higher? Consider 2/3 and 3/4. You know 3/4 > 2/3. Similarly, 15/16 > 14/15. So you eliminate 14/15.

Left with 15/16 vs. 23/25. Here's where I would cross multiply. I'd do 15x25 vs 16x23 and get 375 vs 368. Close call but 15/16 wins it.

Alternatively you could consider 1/16 vs 1/25. They aren't too tough to work with. You can place 1/16 at 0.0625 pretty easily and 1/25 is clearly 0.04. Since you are missing 2/25 that's 0.08 gone. So obviously 15/16 > 23/25 because 15/16 is 1-0.0625 while 23/25 = 1-0.08.


===


For 2 I can only guess as to why that's the answer. I'd also have to see the other choices which I could probably eliminate (aside from x = 4y).

My only guess is that they want b to be the y-intercept. If not then it makes no sense and that isn't the answer. And even if it is it STILL makes no sense. But anyhow... If so, then you have xy = 2b. This is a hyperbola for any b NOT equal to 0. A hyperbola NEVER HITS THE Y-AXIS. So in that case, there will NOT be a value of b! The only way to get a value of b is if b = 0. Then you are left with just x = 0 (from the original equation) which is parallel to the y-axis AND hits (0, 0). The only problem is that it hits EVERY OTHER value of y! You can't have b be the y-intercept if you want the equation to be parallel to the y axis.

Bad question or they gave an explanation of what b is in the problem and you just didn't put it here.

 

[Marmar tala]

Speaking of trig... (Also my weakness in my weak area!)

Can someone explain how to do this:

Which of the following is equal to cos 59 degrees?

sin31
cos31
sin 59
cos(1/59)
Sin (1/50)

*Also if anyone has pointers on any other probable general trig questions, I would love to hear them!

While I'm here...I have some more math questions that give me problems. Although the book has an explanation, I'm just not getting it.


An express train leaves a station 3 hours after a freight train. The express train travels at 60 miles per hour and after 2 hours finds that it is still 20 miles behind the freight train. At what rate is the freight train traveling?


Anne has a total of $34 in nickels, dimes, and quarters. If she has 3 times as many dimes as quarters and two times as many nickels as dimes, how many dimes does she have?


Thanks!!!

first the sin a = cos b when a+b= 90 => if b=59 then a=31

2*60=120 express train after 2 hours, v= freight train speed
120 +20= 5* v => v= 140/5= 28

d:number of dimes, n: # of nickel, q:# of quarters

d=3q , n=2d => (d+2d+d)/10 =34 because every dime is 1/10 $, d=340/4= 85

 

[MoooShuuu]

Anne has a total of $34 in nickels, dimes, and quarters. If she has 3 times as many dimes as quarters and two times as many nickels as dimes, how many dimes does she have?


I don't understand when it says, " she has 3 times as many dimes as quarters, ect" why that makes the equation d=3q.... I always want to write it as 3d=q like if you have 2 dimes, and you have 3 times as many... then you would have 6 dimes compared to quarters. ????

 

[Streetwolf]

Anne has a total of $34 in nickels, dimes, and quarters. If she has 3 times as many dimes as quarters and two times as many nickels as dimes, how many dimes does she have?


I don't understand when it says, " she has 3 times as many dimes as quarters, ect" why that makes the equation d=3q.... I always want to write it as 3d=q like if you have 2 dimes, and you have 3 times as many... then you would have 6 dimes compared to quarters. ????

If you have 3x as many dimes as you have quarters then the number of dimes is 3x the number of quarters. Mathematically you write d = 3q.

If you had 2 quarters you would have 6 dimes.

You can't always take the numbers in the order they give you. You have to reason it out. Think to yourself: which quantity is larger? In this case, you clearly will have more dimes than quarters. Does it make sense, then, to say 3d = q? No! Because whatever your # of dimes is (except for 0), your # of quarters would be larger.

You should be thinking 'the quantity of dimes is triple the quantity of quarters. So if I had a certain amount of quarters, I would need to triple that to find the number of dimes. So if q is the amount of quarters, I would need to multiply q by 3 in order to get d, the amount of dimes'.

Similarly for the dimes/nickels, you have 2x as many nickels as dimes. So if I had a quantity d of dimes, I would have double the quantity of nickels. So if I start with d dimes, I would have 2x this amount, or 2d, of nickels. So n stands for nickels, thus 2d = n.