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Comparison of payment plan of telephone company [#permalink]
28 Mar 2010, 07:59

00:00

A

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D

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Difficulty:

(N/A)

Question Stats:

25% (01:34) correct
75% (02:04) wrong based on 2 sessions

That problem seemed easy but never figured the correct answer, not even with solution provided.... help!

A telephone company offers two plans, A and B. Under plan A, the company charges a total of $0.90 for the first 7 minutes and $0-06 per min thereafter. Under plan B, the company charges $0.08 per min of each call. What is the duration of a call, in minutes, for which the company charges the same amount under plan A and under plan B? A: 2 B: 9 C:15 D:21 E:30

Re: Comparison of payment plan of telephone company [#permalink]
28 Mar 2010, 11:15

1

This post received KUDOS

I think this problem has a typo. If you can, go back to the original GMATPrep screen to verify.

If the answer is as given, I think the problem would have to read "A telephone company offers two plans, A and B. Under plan A, the company charges a total of $0.60 for the first 7 minutes and $0.06 per min thereafter. Under plan B, the company charges $0.08 per min of each call. What is the duration of a call, in minutes, for which the company charges the same amount under plan A and under plan B?"

For the problem as written above, I get 24 as the answer. The equation (amounts in cents, for ease of calculation) is 90 + 6(x-7) = 8x, where x is the number of minutes.

Re: Comparison of payment plan of telephone company [#permalink]
28 Mar 2010, 21:30

nifoui wrote:

That problem seemed easy but never figured the correct answer, not even with solution provided.... help!

A telephone company offers two plans, A and B. Under plan A, the company charges a total of $0.90 for the first 7 minutes and $0-06 per min thereafter. Under plan B, the company charges $0.08 per min of each call. What is the duration of a call, in minutes, for which the company charges the same amount under plan A and under plan B? A: 2 B: 9 C:15 D:21 E:30

Re: Comparison of payment plan of telephone company [#permalink]
28 Mar 2010, 22:23

I defined the variable a little differently because I find I make more mistakes when I subtract than add (for whatever reason). I set "x" to be the number of minutes after the first 7 (which assumed the call would be more than 7 minutes but I figured that was a safe assumption for the question).

0.9 + 0.06x = 0.08(x+7) 0.02x = 0.34 x = 17 Add the first 7 minutes: 17 + 7 = 24 minutes.

Something's off with the question/answer set, just wanted to add a different way to define the variable.