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United Telephone charges a base rate of $10.00 for service,

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by AAPL » Thu Aug 23, 2018 5:49 am

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Manhattan Prep

United Telephone charges a base rate of $10.00 for service, plus an additional charge of $0.25 per minute. Atlantic Call charges a base rate of $12.00 for service, plus an additional charge of $0.20 per minute. For what number of minutes would the bills for each telephone company be the same?

A. 2 minutes
B. 10 minutes
C. 20 minutes
D. 40 minutes
E. 60 minutes

OA D.
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Source: — Problem Solving |

by Brent@GMATPrepNow » Thu Aug 23, 2018 6:00 am
AAPL wrote:Manhattan Prep

United Telephone charges a base rate of $10.00 for service, plus an additional charge of $0.25 per minute. Atlantic Call charges a base rate of $12.00 for service, plus an additional charge of $0.20 per minute. For what number of minutes would the bills for each telephone company be the same?

A. 2 minutes
B. 10 minutes
C. 20 minutes
D. 40 minutes
E. 60 minutes

OA D.
Let x = the number of minutes used

United Telephone charge = $10.00 + $0.25x
Atlantic Call charge = $12.00 + $0.20x

For what number of minutes would the bills for each telephone company be the same?
In other words, for what value of x does $10.00 + $0.25x EQUAL $12.00 + $0.20x?

Let's find out....
10.00 + 0.25x = 12.00 + 0.20x
Subtract 10 from both sides to get: 0.25x = 2 + 0.20x
Subtract 0.20x from both sides to get: 0.05x = 2
Solve: x = 2/0.05 = 40

ASIDE: If you're not crazy about dividing by decimals, you can always take 2/0.05 and create an EQUIVALENT fraction first.
Take: 2/0.05
Multiply top and bottom by 100 to get: 200/5, which equals 40

Answer: D

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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by GMATGuruNY » Thu Aug 23, 2018 6:16 am
AAPL wrote:Manhattan Prep

United Telephone charges a base rate of $10.00 for service, plus an additional charge of $0.25 per minute. Atlantic Call charges a base rate of $12.00 for service, plus an additional charge of $0.20 per minute. For what number of minutes would the bills for each telephone company be the same?

A. 2 minutes
B. 10 minutes
C. 20 minutes
D. 40 minutes
E. 60 minutes
An alternate approach is to PLUG IN THE ANSWERS.
When the correct answer is plugged in, the two companies will charge the same amount.

B: 10 minutes
Since United charges $10 plus $0.25 per minute, the charge from United = 10 + 10(0.25) = $12.50.
Since Atlantic charges $12 plus $0.20 per minute, the charge from Atlantic = 12 + 10(0.20) = $14.00.
In this case, United's charge is lower than Atlantic's.
Eliminate B.

D: 40 minutes
Since United charges $10 plus $0.25 per minute, the charge from United = 10 + 40(0.25) = $20.
Since Atlantic charges $12 plus $0.20 per minute, the charge from Atlantic = 12 + 40(0.20) = $20.
Success!

The correct answer is D.
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by Jeff@TargetTestPrep » Wed Sep 05, 2018 9:48 am
AAPL wrote:Manhattan Prep

United Telephone charges a base rate of $10.00 for service, plus an additional charge of $0.25 per minute. Atlantic Call charges a base rate of $12.00 for service, plus an additional charge of $0.20 per minute. For what number of minutes would the bills for each telephone company be the same?

A. 2 minutes
B. 10 minutes
C. 20 minutes
D. 40 minutes
E. 60 minutes
We can let n = the number of minutes and create the equation:

10 + 0.25n = 12 + 0.2n

0.05n = 2

n = 40

Answer: D

Jeffrey Miller
Head of GMAT Instruction
[email protected]

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