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

Redeem

2 GMAT Prep Questions

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Junior | Next Rank: 30 Posts
Posts: 16
Joined: Fri Apr 06, 2007 8:14 pm

2 GMAT Prep Questions

by MonicaKhan » Sun Apr 22, 2007 3:31 pm
If anyone knows how to do either of the questions below, please let me know - thanks!

The temperature of a certain cub of coffee 10 minutes after it was poured was 120 degrees Fahrenheit. If the temperature F of the coffee t minutes after it was poured can be determined by the formula F = 120(2^-at) + 60, where F is in degrees Fahrenheit and is a constant, then the temperatre of the coffee 30 minutes after it was poured was how many degrees Fahrenheit?

(A) 65
(B) 75 (this is the answer)
(C) 80
(D) 85
(E) 90

The total of Company C's assets in 1994 was 300 percent greater than the total in 1993, which in turn was 400 percent greater than the total in 1992. If the total of Company C's assets in 1992 was N dollars, which of the following represents tht toal of Company C's assets, in dollars, in 1994?

A) 7N
B) 8N
C) 9N
D) 12N
E) 20N (this is the answer)

The answer is E, but I think it should be D.
Top
Source: — Problem Solving |
User avatar
Community Manager
Posts: 789
Joined: Sun Jan 28, 2007 3:51 pm
Location: Silicon valley, California
Thanked: 30 times
Followed by:1 members

Re: 2 GMAT Prep Questions

by jayhawk2001 » Sun Apr 22, 2007 5:22 pm
MonicaKhan wrote:If anyone knows how to do either of the questions below, please let me know - thanks!

The temperature of a certain cub of coffee 10 minutes after it was poured was 120 degrees Fahrenheit. If the temperature F of the coffee t minutes after it was poured can be determined by the formula F = 120(2^-at) + 60, where F is in degrees Fahrenheit and is a constant, then the temperatre of the coffee 30 minutes after it was poured was how many degrees Fahrenheit?
First compute 'a' given the 10-min info
120 = 120 (2^(-10a)) + 60
2^-1 = 2^-10a
a = 1/10

Now, compute the 30 min info
F = 120(2^(-30/10)) + 60
= 120 * 2^-3 + 60
= 15 + 60
= 75
MonicaKhan wrote:
The total of Company C's assets in 1994 was 300 percent greater than the total in 1993, which in turn was 400 percent greater than the total in 1992. If the total of Company C's assets in 1992 was N dollars, which of the following represents tht toal of Company C's assets, in dollars, in 1994?

Lets call assets in 1993 as x and 1994 as y. We have to find y/N

x = 4N + N (x is 400% greater than N, so it is actually 5N)
x = 5N

Similarly --
y = 4x = 4*5*N = 20N
y/N = 20
Top
Legendary Member
Posts: 559
Joined: Tue Mar 27, 2007 1:29 am
Thanked: 5 times
Followed by:2 members

by Cybermusings » Sun Apr 22, 2007 11:22 pm
F = 120(2^-at) + 60 (f = temp of coffee "t" min after it was poured and "a" is a constant
Substituting 120 for F and 10 for t
120 = 120(2^-10a)+60
120-60 = 120(2^-10a)
60/120 = 2^-10a
1/2=2^-10a
1/2=1/2^10a
1=10a (equating the respective powers since the base is the same
Thus a =1/10

Now when t=30
F= 120[2^(-30*1/10)]+60
F=120(2^3)+60
F=120(2^-3)+60
=[120*(1/2^3)]+60
=(120/8 )+60
=75
Top
Legendary Member
Posts: 559
Joined: Tue Mar 27, 2007 1:29 am
Thanked: 5 times
Followed by:2 members

by Cybermusings » Sun Apr 22, 2007 11:25 pm
1992 = N
1993=N + 400N/100 = 5N
1994=5N + 300*5N/100 = 5N+15N=20N
Top
Post new topic Post Reply
• Page 1 of 1