BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

cake recipe

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 641
Joined: Tue Feb 14, 2012 3:52 pm
Thanked: 11 times
Followed by:8 members

cake recipe

by gmattesttaker2 » Wed Feb 19, 2014 6:44 pm
Hello,

Can you please tell me how to solve the following:

A certain cake recipe states that the cake should be baked in a pan 8 inches in diameter. If Jules wants to use the recipe to make a cake of the same depth but 12 inches in diameter, by what factor should he multiply the recipe ingredients?

A) 2 1/2
B) 2 1/4
C) 1 1/2
D) 1 4/9
E) 1 1/3

OA: B

Thanks,
Sri
Top
Source: — Problem Solving |
User avatar
Master | Next Rank: 500 Posts
Posts: 490
Joined: Thu Jul 04, 2013 7:30 am
Location: Chennai, India
Thanked: 83 times
Followed by:5 members

by Uva@90 » Wed Feb 19, 2014 9:33 pm
gmattesttaker2 wrote:Hello,

Can you please tell me how to solve the following:

A certain cake recipe states that the cake should be baked in a pan 8 inches in diameter. If Jules wants to use the recipe to make a cake of the same depth but 12 inches in diameter, by what factor should he multiply the recipe ingredients?

A) 2 1/2
B) 2 1/4
C) 1 1/2
D) 1 4/9
E) 1 1/3

OA: B

Thanks,
Sri
Sri,
Actual Radius is 4
Final radius is 6

you have to compare by the square of the radius

4^2 and 6^2
16 and 36

so, 16*9/4 =36
Hence answer is B

Regards,
Uva.
Known is a drop Unknown is an Ocean
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 359
Joined: Wed Mar 11, 2009 4:37 am
Location: Kolkata, India
Thanked: 50 times
Followed by:2 members

by Abhishek009 » Thu Feb 20, 2014 10:10 am
gmattesttaker2 wrote:A certain cake recipe states that the cake should be baked in a pan 8 inches in diameter. If Jules wants to use the recipe to make a cake of the same depth but 12 inches in diameter, by what factor should he multiply the recipe ingredients?
Jules must necessarily be baking the cake in a Cylindrical container ( having some height at least )

Given the Original Diameter is 8 Inches , hence radius will be 4 inches

Let the depth of the Container be D

So , volume of the cake is - π4²D => 16πD


Now Jules wants to keep the Depth of the container the same and wants to increase the diameter to 12 Inches ( probably he has invited some other people for the party) , so the radius of the proposed cake will be 6 inches.

So , Volume of the cake proposed to be bakes is = π6²D => 36πD


So , Jules must mix the ingredients in the ratio of New Volume / Actual Volume according to Recipe

For baking the desired diameter of Cake Jules must now multiply his ingredients by -

=> 36Ï€D / 16Ï€D => 9/4 = 2 and 1/4th

Hence Answer will be (B)
Abhishek
Top
GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Thu Feb 20, 2014 2:28 pm
A general approach that will work no matter what numbers you have:

Volume/area of new cake
-----------------------
Volume/area of old cake

In this case, the "area" (shouldn't this be a 3D cake? Oh well ...) of the old cake is πr², or π*4², or 16π. The area of the new cake is π*6² = 36π. 36π / 16π = 2.25, and you're done - that's the factor by which you'd have to multiply.
Top
Post new topic Post Reply
• Page 1 of 1