A jar of peanut butter which is 3 inches in diameter and 4 inches high sells for $0.60. At the same rate, what would be the price for a jar that is 6 inches in diameter and 6 inches high?

5 answers

V = ( d ^ 2 * pi / 4 ) * h

V1 = ( 3 ^ 2 * pi / 4 ) * 4 = ( 9 * pi / 4 ) * 4 = 36 * pi / 4

V2 = ( 6 ^ 2 * pi / 4 ) * 6 = ( 36 * pi / 4 ) * 6 = 216 pi / 4

V2 / V1 = ( 216 * pi / 4 ) / ( 36 * pi / 4 ) = 216 / 36 = 6

6 * 0.6 $ = 3.6 $
volume = π(1.5)^2 (4)
= 9π cubic inches

volume of new jar π(3^2)(6) = 54π cubic inches
which is 6 times the original
So the new one should cost 6(.60) or $3.00
oops , typo

6 x 60cents = $3.60
Thanks Reiny and Bosian!!!
OR

V = ( d ^ 2 * pi / 4 ) * h

V1 = ( 3 ^ 2 * pi / 4 ) * 4 = ( 9 * pi / 4 ) * 4 = 9 pi in ^ 3

V2 = ( 6 ^ 2 * pi / 4 ) * 6 = ( 36 * pi / 4 ) * 6 = 216 pi / 4 = 54 pi in ^ 3

V2 / V1 = 54 pi / 9 pi = 54 / 9 = 6

6 * 0.6 $ = 3.6 $