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

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

Temperature problem

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Master | Next Rank: 500 Posts
Posts: 207
Joined: Mon Oct 06, 2008 12:22 amFollowed by: 3 members
Location: India
Thanked: 5 times
by The Jock » Wed Oct 08, 2008 5:46 am
the temperature of a certain cup 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 a is a constant, then the temperature of the coffee 30 minutes after it was poured was how many degrees faherenheit?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Junior | Next Rank: 30 Posts
Posts: 17
Joined: Mon Sep 29, 2008 12:24 pm
Thanked: 1 times

by ab78 » Sat Oct 11, 2008 11:53 am
The temp f=120(2^-at) + 60

after 10 mins given temp is 120, substituting

120-60 = 120(2^-a10)

1/2=2^-10a

10a=1 therefore a= 1/10

now substitute after 30 mins f = 120(2^-3) + 60 = 75

wat is the answer?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 114
Joined: Mon Oct 20, 2008 7:03 pmFollowed by: 5 members
Thanked: 4 times

by jnellaz » Fri Nov 07, 2008 6:33 am
Hey ab78 -

Can you explain how you got from

1/2=2^-10a

to

10a=1?

I lost you on that.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 207
Joined: Sun Mar 11, 2007 6:16 pm
Location: Mumbai
Thanked: 11 times

by jimmiejaz » Fri Nov 07, 2008 7:39 am
jnellaz wrote:Hey ab78 -

Can you explain how you got from

1/2=2^-10a

to

10a=1?

I lost you on that.
1/2 = 2^-1.
comparing both sides we get,
-1=-10a
a=1/10

hope u r clear now.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Newbie | Next Rank: 10 Posts
Posts: 2
Joined: Sat Nov 08, 2008 2:25 am

by stickyfingers48 » Sat Nov 08, 2008 7:01 am
Hey ab78 -

Can you explain how you got from

1/2=2^-10a

to

10a=1?

I lost you on that.


Substitute this value of a in the following equation:

F= 120*(2^-10/a) +60

The answer is 75
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1