1 simple math question?

[Dencology]

Advertisement - Members don't see this ad

guys can you tell me if this is % inc. or dec.

the price of one share of a company's stock rose by 20% one day then dropped by 5% the next day. what was the overall percentage change in the price of the stock over these two days?

a. 8%
b. 10%
c. 12.5%
d. 14%
e. 15%


i thought that i would do the following:

since it rose 20% then it would be 120 but then dropped 5% so it would be 114% inc. from the original price. so it would be 14% inc. right?

another problem:

when the line 2x + 3y =12 is graphed in the x-y plane, it forms a triangle with the coordinates axes. what is the are of this triangle?

a. 6
b. 8
c. 10
d. 12
e. 18


if |1-2X| < 5, then X can be no less than

• -3
• -2
• 1
• 2
• 3

i always get inequalities wrong. guys can you help me with how to do inequalities?

 

[jdent]

yes

 

[AndyK]

Problem 1:

100 * 1.2 * 95/100 = 95 + (.2)(95) = 95 + 19 = 114 so the anser is 14%

Problem 2:
2x + 3y = 12
Setting y to 0 gives you the x-int, setting x to 0 gives you the y-int.
2x = 12, x-int = 6
3y = 12, y-iny = 4

Triangle area = 1/2bh, so the answer is 1/2*4*6 = 12

 

[Dencology]

what about the third prob.?

 

[AndyK]

On that problem I would just quickly plug in the answer choices

for A, |1-2(-3)| <= 5, |7| <= 5 so that's wrong
for B, |1-2(-2)| <= 5, |5| <=5 and that's correct

They're looking for the smallest number that makes the inequality correct, so the other choices are wrong even though the inequality still works.

 

[PooyaH]

what about the third prob.?

Third one is saying what the minimum number x could be so the result we get on the left side is no more than 5!
So the fastest way is to plug in the answer choices, which happens to be -2!

Since it has the absolute value, all the answers are going to be a positive integer. So:
l1-2(-2)l = 5
So -2 is the mimium number x could be! If you put -3 for x then you get l1-2(-3)l = 7 which would be more than 5!

 

[Streetwolf]

1-2x </eq 5 (I'm just writing < or > from now on, assume the = is there)

-2x < 4
x > -2

So x is > or equal to -2.

If you did the other part of the abs value you'd have:

1-2x >/eq -5
-2x > -6
x < 3

So x is < or equal to 3.

Your range is [-2, 3]. The problem wants the minimum which is -2. I guess it would be easiest to plug in numbers on this problem.