Geometry Strategy Guide (Question 7 - Page 49)

[HARISH]

Hi everyone,

I have a doubt with question 7 - Page 49.

"Red Giant cola comes in 2 sizes, Giant and Super Giant. Each comes in a cylindrical container, and the Giant size sells for $1.20. If the Super-Giant container has twice the height and its circular base has twice the radius of the Giant size, and the price per ml of Red Giant cola is the same, how much does the Super-Giant container cost?"

I think the Vol of Super Giant should be = 3.14(pi) x r x r x 2h.
However, according to the book, Vol of Super Giant should be = 3.14(pi) x 2r x 2r x 2h.

How come the radius of Super Giant is 2r? The word "circular base" should be referring to the Diameter.

Any thoughts?

[Harish Dorai]

Harish -

The radius for the Super Giant is 2r because as per the question, the Super Giant is having twice the radius of the Giant size.

So assuming Giant size cola can has a Circular base radius of "r" and height "h". Its volume is PI x r x r x h = say "G".

For Super giant volume = PI x (2r) x (2r) x (2h)
= 8 x PI x r x r x h
= 8 x G

So the Super Giant volume is 8 times the volume of Giant size. So its price will be 8 times the price of Giant size.

hope it helps.

[JadranLee]

That's right, Harish Dorai. Thanks for answering the question.

-Jad