Cant figure it out! : Quant Question Archive [LOCKED]
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# Cant figure it out!

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Intern
Joined: 14 Sep 2007
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24 Sep 2007, 17:28
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

this seems so easy, but i dont get the correct answer!?!

A certain phone company offers two plans, A and B. Under plan A, the company charges a total of $.60 for the first 7 minutes of each call and$.06 per minute thereafter. Under plan B, the company chargers $.08 per minute of each call. What is the duration of a call, in minutes, for which the company charges the same amount under plan A and under plan B? A. 2 B. 9 C. 15 D. 21 E. 30 (OA is B, 9 mins) VP Joined: 09 Jul 2007 Posts: 1104 Location: London Followers: 6 Kudos [?]: 103 [0], given: 0 Re: Cant figure it out! [#permalink] ### Show Tags 24 Sep 2007, 17:39 GMAT4Lyfe wrote: this seems so easy, but i dont get the correct answer!?! A certain phone company offers two plans, A and B. Under plan A, the company charges a total of$.60 for the first 7 minutes of each call and $.06 per minute thereafter. Under plan B, the company chargers$.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

(OA is B, 9 mins)

Plan A:
7 -----> 0.6 total for the first 7 mins
X------>0.06 per min

Plan B:
(X+7) mins charge 0.08 per min

now, total charge in Plan A is 0.6+0.06X
then total charge in Plan B is 0.08(X+7)

0.6+0.06X=(X+7)0.08
0.02X=0.04
X=2

total time 7+2=9
GMAT Club Legend
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24 Sep 2007, 19:38
Assume the # if minutes is x.

Then

0.6 + (x-7)(0.06) = 0.08x
0.6 + 0.06x - 0.42 = 0.08x
0.02x = 0.18
x = 9 mins
Director
Joined: 09 Aug 2006
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Re: Cant figure it out! [#permalink]

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24 Sep 2007, 20:29
GMAT4Lyfe wrote:
this seems so easy, but i dont get the correct answer!?!

A certain phone company offers two plans, A and B. Under plan A, the company charges a total of $.60 for the first 7 minutes of each call and$.06 per minute thereafter. Under plan B, the company chargers $.08 per minute of each call. What is the duration of a call, in minutes, for which the company charges the same amount under plan A and under plan B? A. 2 B. 9 C. 15 D. 21 E. 30 (OA is B, 9 mins) Plan A : 0.60+0.06+0.06 = 0.72 Plan B 0.08 * 9 = 0.72 Ans is 9 mins. Director Joined: 03 Sep 2006 Posts: 879 Followers: 6 Kudos [?]: 770 [0], given: 33 Re: Cant figure it out! [#permalink] ### Show Tags 24 Sep 2007, 21:10 GMAT4Lyfe wrote: this seems so easy, but i dont get the correct answer!?! A certain phone company offers two plans, A and B. Under plan A, the company charges a total of$.60 for the first 7 minutes of each call and $.06 per minute thereafter. Under plan B, the company chargers$.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

(OA is B, 9 mins)

Let's assume that the call is made for X minutes.

Plan A Tariff:

$0.60 + (X-7)*$0.06

Plan B Tariff:

X*$0.08 X*0.08 = 0.60 + (X-7)*0.06 which gives X = 9. CEO Joined: 29 Mar 2007 Posts: 2583 Followers: 19 Kudos [?]: 421 [0], given: 0 Re: Cant figure it out! [#permalink] ### Show Tags 24 Sep 2007, 21:17 GMAT4Lyfe wrote: this seems so easy, but i dont get the correct answer!?! A certain phone company offers two plans, A and B. Under plan A, the company charges a total of$.60 for the first 7 minutes of each call and $.06 per minute thereafter. Under plan B, the company chargers$.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

(OA is B, 9 mins)

X: number of minutes.

So .60 for first 7 mintes and .06 per min after.

Other company is .08 per min. When will these be equal. elim decimals to make this easier.

Write out an eqaution: 60+6x=8(x+7) We need to have x+7 b/c the 60 in the first half of the eqauation basically stands for the first 7minutes, we have to represent this on the second half.

so 60+6x=8x+56 2x=4 x=2. So we have 7+2 = 9.

B.
Intern
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25 Sep 2007, 05:53
oh my god im so stupid..i read the question wrong...i thought it said plan A charges .60 for EACH minute up to 7 then .06 7+...man, I gotta pay more attention

thanks a lot guys!
25 Sep 2007, 05:53
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