# Ok I tried can someone check to see if I am right please.

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Posted by Desire on October 14, 2002 at 00:45:04:

In Reply to: homework help posted by desire on October 13, 2002 at 20:08:38:

: 1) The volume of a cone is V= 1/3 Pie r squared. Rewrite th formula for H in tems of V nd R?? please show the steps please..

I still can't do that one, I don't undestand what happened to the H :(
: 2) If A is directly proportional to the cube of b, write the equation.

A= k (b^3)
: 11) Mrs Johnon is 3 times as old as her son. Ten years ago she was 5 times as old as her son was then. Find Mrs Johnon's present age?

Son = x
Mrs J = 3x
5(x - 10) = 3x -10
5x - 50 = 3x-10
2x = 40
x = 20

5(25) - 10 = 125 -50 = 75
20*3 = 60 is Mrs. J
10 year ago mrs j was 50 and her son was 10, wow she was 40 when she had him.
: 12) John in 5 years older then Mary. Ten years from now,the sum of their ages will be 39. How old is John now?
John = J
Mary = M
J = 5 + M
J + M = 39
5+M + M = 39
2M = 34
M = 17
so J = 22
check 17 + 22 = 39

: 13) Jaime has a 15% discount coupon for Foleys Red apple Sale. If se buys a shirt for \$25 and jeans for \$35 (regular price), write an equation that show the
: A) discount she would get
(25+35)*.15 = 9
: b) amount she would pay with the discount coupon
(25+35)*(1-.15)= 51
so she pays \$51 for the stuff
: 14) a) If y varies directly as x and y=-16 when x=2 find y when x=-12
y = k x
-16= (k) 2
-8 = k
y = (-8)(-12)
y= 96
I am not sure if this is right

: b) If y varies directly as x and y=-12 when x=-18, find x when y=24
y = k x
-12 = (k)(-18)
-12/-18 = k
2/3=k
24/(2/3)=x
x = 36
I am not sure if this is right

: 16) write variation equaion for the following:
: a) intesity I of lightvarie inversely as the square of the observers distance d from the light source
I = k/(d)^2
I am not sure if this is right
: b) price of pizza p varies diectly with the square of its diameter
p = k(d^2)

: 20) one number is twice another #. If u take one-fourth of the lesser # and subtract it from the greater # u get 21 find the leser # and the greater #??
x = 2y
(x/4)-2y=21
(2y/4)-2y = 21
(2y)-8y=84
6y=64
y = 8
so the lesser would be 4 since 4 = (8/2) and the greater would be 8.

: 21) Rent--Truck's rates are \$50 per day plus \$0.50 per mile and Sam's U-Drive's are \$70 a day plus \$).45 per mile.
: a) Find the mileage at which the cost for the two will be the same?
50 + (.5x) = 70 + (.45x)
.05 x = 20
Rent Trucks = 50 +(.50*400) = \$250
U drive = 70 + (.45 * 400) = \$250

: c) when should u rent from rent a truck rather than Sams u-drive?
when you are going to drive more than 400 miles.
: D) When should u rent rom Sams U-drive rather than Rent a truck? When you are going to drive less than 400 miles

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