A certain telephone company offers two plans, A and B. Under

Question

A certain telephone company offers two plans, A and B. Under plan A, the company charges a total of $0.60 for the first 7 minutes of each call and $0.06 per minute thereafter. Under plan B, the company charges $0.08 per minute 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

A. 2 
B. 9 
C. 15 
D. 21 
E. 30

Bunuel · Accepted Answer

A certain telephone company offers two plans, A and B. Under plan A, the company charges a total of $0.60 for the first 7 minutes of each call and $0.06 per minute thereafter. Under plan B, the company charges $0.08 per minute 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

A. 2 
B. 9 
C. 15 
D. 21 
E. 30

Let the duration, in minutes, for which the company charges the same under plan A and plan B be t minutes.

Then under plan A the cost would be $0.6+0.06(t-7) and under plan B the cost would be $0.08t. We want these amount to be equal: 0.6+0.06(t-7)=0.08t --> 60+6(t-7)=8t --> t=9.

Answer: B.

Hope it's clear.

TomB · Answer

why dont we write this equation like this:
number of minutes be X

0.6(7)+0.06(x-7)=0.08(x). whats wrong with this equation.

according to manhattann word translation guide

Ex: pay $10 for the first 2 CDs then $7 per additional CD. 
N is number of CDs bought.
10*2+7(n-2)=T.C

what is the difference

Bunuel · Answer

The red part is wrong because the company charges a  total  of $0.60 for the first 7 minutes and not $0.60 per each minute of the first 7 minutes.

In your example I guess it's meant that $10 are paid  for each  of the first 2 CD's.

Hope it's clear.

shivanigs · Answer

Let the total duration of the call be x minutes.

Plan A = 0.60 + 0.06(x-7)

Plan B = 0.08x

Since both the amounts charged are equal, 0.60 + 0.06(x-7) = 0.08x
 
-0.02x = -0.18

Hence x = 9 minutes

cht1128 · Answer

In the first 7 mins:
Plan A cost 0.6
Plan B cost 0.08*7=0.56
0.6-0.56= 0.04  <-  Plan A  cost 0.04 more

After 7 mins:
Plan A cost 0.06 per min
Plan B cost 0.08 per min
0.08-0.06= 0.02  <-  Plan B  will cost 0.02 more per min

To balance the cost between Plan A and B:
 0.04 = 0.02 * 2

7+ 2 =9 is the answer

PareshGmat · Answer

Solved by plugging-in the options

For 2 Minutes, 
Plan A = 7; 
Plan B = 0.16

For 9 Minutes, 
Plan A = 0.6 + 2* 0.06 = 0.6 + 0.12 = 0.72
Plan B = 0.08 * 9 = 0.72

Answer = B

ScottTargetTestPrep · Answer

We can let m = the duration of the call, in minutes, and create the equation:

0.6 + 0.06(m - 7) = 0.08m

0.6 + 0.06m - 0.42 = 0.08m

0.18 = 0.02m

9 = m

Answer: B

EMPOWERgmatRichC · Answer

Hi All,

We're told that a certain telephone company offers two plans, A and B. Under plan A, the company charges a total of $0.60 for the FIRST 7 minutes of each call and $0.06 per minute thereafter. Under plan B, the company charges $0.08 per minute of each call. We're asked for the duration of a call, in minutes, for which the company charges the SAME amount under plan A and under plan B. This question can be solved in a couple of different ways, including by TESTing THE ANSWERS.

Since Plan A charges a fixed amount for the first 7 minutes, while Plan B charges a higher per-minute rate (8 cents vs. 6 cents), and those numbers are all relatively small, it's likely that the correct answer will be relatively small. Let's TEST Answer B first.

Answer B: 9 minutes 
Plan A = $0.60 for the first 7 minutes + ($0.06)(2 extra minutes) = $0.60 + $0.12 = $0.72 
Plan B = ($0.08)(9 minutes) = $0.72 
These two totals are the same, so this must be the answer.

Final Answer:  B

GMAT assassins aren't born, they're made, 
Rich

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A certain telephone company offers two plans, A and B. Under

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