RozhonDDS

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PLease HELP!!!

1) y=(2x+1)/(x-3), solve for x
ANS: x=(3y+1)/(x-2)


2)$ 180 is to be shared between james and henry so that henry has 25% more than james. How much does james get?
ANS:80

3) Anne's ski boat can travel 20mph in calm water. On a river the boat could travel 45miles trageling with the current in the same time that it could travel 27 miles against the current. What is the rate of the current in mph?

ANS:5

4) Two runners start at the same place and run in opposite directions around a two mile oval track. One runs at 10mi/hr while the other runs at 15mi/hr. How long before they meet?

ANS:4.8

5)A pair of 6 sided dice are thwon simulataneously. What is the probability that the sum of the two numbers showing is greater than 3?

ANS: 11/12
 

AFUA

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RozhonDDS said:
PLease HELP!!!

1) y=(2x+1)/(x-3), solve for x
ANS: x=(3y+1)/(x-2)

2x + 1 = y(x-3)
2x + 1 = yx -3y
1+ 3y = yx - 2x
1+ 3y = x( y-2)
x = (1+3y)/ (y-2)

I think the denominator in the answer can't x-2 since you are solving for x.
 
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AFUA

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2)$ 180 is to be shared between james and henry so that henry has 25% more than james. How much does james get?
ANS:80

let the amount that james receives = x
thus, henry will receive= x + 0.25x

x+ (x + 0.25X) = 180
2.25x = 180
x = 180/2.25 = $80
 

Banana Berry

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throw 2 dices simulataneously you can get 6^2=36 combinations. There are 3 total combinations that you can get for equal or less than 3: 1+1, 1+2, or 2+1. The chance of getting the 3 combinations is 3/36=1/12. Therefore, the chance of getting greater than 3 is 1-1/12= 11/12.
 

wigglytooth

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4) Two runners start at the same place and run in opposite directions around a two mile oval track. One runs at 10mi/hr while the other runs at 15mi/hr. How long before they meet?

ANS:4.8

d=r*t

The distance traveled is different but the time they meet has to be the same --> manipulate the equation: t = d/r

d1/r1 = d2/r2

You don't know how far they would travel before the times are equal, so you need to come up with an equation for both d's. Since they both can't run more than 2 mi, one d = x and the other is 2-x (it really doesn't matter which is which).

x/r1 = (2-x)/r2

Plug the rates and solve for the distance traveled. Now all that's left is finding out how long it took them to meet. Plug one set of data into t = d/r (doesn't matter which, as long as the data entered is for only one runner). You should get 4.8.
 

yorkiepoo

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You must convert the speeds to mile/min. so from 10 and 15 mph you get 1/6 and 1/4 mile/min. then find common denominator so they become 2/12 and 3/12 mile/min. consider the 2 mil track as a line and each runner is running from opposite ends (since the fact that it is oval really doesn't make the problem easier, just simplify it for yourself). So 2 mil can be written as 24/12. We know that the total amount that runners 1 and 2 will run before meeting will be 2 miles, but you can think of it as 24 segments they have to run. So runner 1 can run 2 segment per min. and runner 2 can run 3 segments per min. So consider how much they would have run after 1, 2, 3 etc min. So you would see:

1min: 2 + 3 = 5
2min: 4 + 6 = 10
3min: 6 + 9 = 15
4min: 8 + 12 = 20 (close!)
5min: 10 + 15 = 25 (a little too much)

So you know that somewhere between 4 and 5 (closer to 5) min they would have reached eachother. :idea:
 

claydds

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wigglytooth said:
4) Two runners start at the same place and run in opposite directions around a two mile oval track. One runs at 10mi/hr while the other runs at 15mi/hr. How long before they meet?

ANS:4.8

d=r*t

The distance traveled is different but the time they meet has to be the same --> manipulate the equation: t = d/r

d1/r1 = d2/r2

You don't know how far they would travel before the times are equal, so you need to come up with an equation for both d's. Since they both can't run more than 2 mi, one d = x and the other is 2-x (it really doesn't matter which is which).

x/r1 = (2-x)/r2

Plug the rates and solve for the distance traveled. Now all that's left is finding out how long it took them to meet. Plug one set of data into t = d/r (doesn't matter which, as long as the data entered is for only one runner). You should get 4.8.
:idea:
 
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RozhonDDS

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Can someone also explain this question.

I know what the neg reciprocal is but i'm not sure why the y-intercept is X


1) Which of the following is the equation of the line that contains the point (3,-1) and is perpendicular to the line y=3x+3
ANS: y=(-1/3)


2)What is the maximum number of 3-inch squares that can be cut from a sheet of tin 19x22 inches?
ANS: 42

THANK YOU
 

dontbam

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RozhonDDS said:
Can someone also explain this question.

I know what the neg reciprocal is but i'm not sure why the y-intercept is X


1) Which of the following is the equation of the line that contains the point (3,-1) and is perpendicular to the line y=3x+3
ANS: y=(-1/3)


2)What is the maximum number of 3-inch squares that can be cut from a sheet of tin 19x22 inches?
ANS: 42

THANK YOU

for #1) you know the slope of the line for anything perpendicular to the original equation is always the negative reciprical or (-1/3), then look at your answer choices and plug in the numbers ie (3, -1) fastest approach

for 2) dont multiple 19x22 because you wont get perfect 3x3 squares doing that, so just look at 19 inches, how many 3 inch portions can be cut from that? Yup that's right, 6...now look at 22, you can cut out approx 7. So now you have 6 x 7 or 42.

Good luck
 

cryptozoologist

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3) Anne's ski boat can travel 20mph in calm water. On a river the boat could travel 45miles trageling with the current in the same time that it could travel 27 miles against the current. What is the rate of the current in mph?

ANSWER: R = D/T

Times equate so rearrange eq: T = dist / rate

Ru/Du = Rd/Rd (where u = upstream, d = downstream)

27/(20-x) = 45/(20+x)

72x = 360

x = 5
 
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RozhonDDS

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I"m still confused on the question that goes

What is the equation of a line that is on point (3,-1) and is perpindicular to y=3x+3

ANS:y=(-1/3)x


What do i plug the (3,-1) into to get the y-intercept?
 

SkiBabeUSF

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use this formula to get the equation of a line.
y-y1=m(x-x1)

(the 1's are subscripts)




RozhonDDS said:
I"m still confused on the question that goes

What is the equation of a line that is on point (3,-1) and is perpindicular to y=3x+3

ANS:y=(-1/3)x


What do i plug the (3,-1) into to get the y-intercept?
 
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