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20 Jun 2016, 10:04
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Last month a phone company charged $0.07 per minute for the first 300 minutes of calling time and$0.05 per minute for each minute of calling time in excess of the first 300 minutes . For how many minutes of calling time was Bob charged by the phone company last month?

1) Last month the phone company charged Bob $21.00 for his calling time that was charged at$0.07 per minute.

2) Last month the phone company charged Bob $40.00 for his calling time that was charged at$0.05 per minute.
[Reveal] Spoiler: OA

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Re: Last month a phone company charged $0 .07 [#permalink] ### Show Tags 21 Jun 2016, 06:11 C for me 1)gives time for .07 minute call .he talked for amount 21$=300 minutes.not suff(no inf about 0.05 call)
2) 40$for 0.05 call i.e 800 minutes.not suff(no info about 0.07 call) C-total of 1100 minutes Kudos [?]: 92 [0], given: 4 Math Expert Joined: 02 Aug 2009 Posts: 5365 Kudos [?]: 6157 [5], given: 121 Re: Last month a phone company charged$ 0 .07 [#permalink]

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21 Jun 2016, 06:33
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Skywalker18 wrote:
Last month a phone company charged $0.07 per minute for the first 300 minutes of calling time and$0.05 per minute for each minute of calling time in excess of the first 300 minutes . For how many minutes of calling time was Bob charged by the phone company last month?

1) Last month the phone company charged Bob $21.00 for his calling time that was charged at$0.07 per minute.

2) Last month the phone company charged Bob $40.00 for his calling time that was charged at$0.05 per minute.

Hi hsbinfy and manishpatwal,

ans should not be C or D, it should be B..

the Q tells you..
first 300 = 0.07 per minute
after 300 = 0.05 per minute..
we have to find TOTAL time..

lets see the statements-

1) Last month the phone company charged Bob $21.00 for his calling time that was charged at$0.07 per minute.
we do not anything about the minutes beyond 300..
Insuff

2) Last month the phone company charged Bob $40.00 for his calling time that was charged at$0.05 per minute
We know now how many minutes did he speak in excess of 300 =$$\frac{40}{0.05}= 800$$ minutes..
ans = 300+800 = 1100
Suff

B
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Re: Last month a phone company charged $0 .07 [#permalink] ### Show Tags 21 Jun 2016, 09:55 1 This post received KUDOS Skywalker18 wrote: Last month a phone company charged$ 0.07 per minute for the first 300 minutes of calling time and $0.05 per minute for each minute of calling time in excess of the first 300 minutes . For how many minutes of calling time was Bob charged by the phone company last month? 1) Last month the phone company charged Bob$21.00 for his calling time that was charged at $0.07 per minute. 2) Last month the phone company charged Bob$40.00 for his calling time that was charged at $0.05 per minute. IMO, Answer must be B. 1) Last month the phone company charged Bob$21.00 for his calling time that was charged at $0.07 per minute. This statement says Bob made calls for 300 mins for which he was charged$21. But it doesn't tell if Bob called only for 300 minutes or more.

not sufficient.

2) Bob was charged $40 at the rate 0.05/minute. So the minutes he was charged at this rate were= 40/.05= 800 minutes But, since this rate is over 300 minutes. So the total minutes he was charged for were= 800+300= 1100 minutes Sufficient. _________________ I welcome critical analysis of my post!! That will help me reach 700+ Kudos [?]: 456 [1], given: 69 Intern Joined: 02 Jun 2016 Posts: 41 Kudos [?]: 25 [0], given: 5 Schools: Sloan '19 (II) Last month a phone company charged$ 0 .07 [#permalink]

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21 Jul 2016, 18:55
I have a question about answer choice B and any help on this question would be much appreciated. B states that Bob was charged 40 bucks at 5 cents per minute, so his total minutes at that rate amounts to 800. Ok, got it so far. What I don't get is that under this statement, it is still possible for the number of minutes at the 7 cent/min rate to vary. For example, couldn't Bob have made one giant 1100 minute call, where he stays on the phone 800 mins past the initial 300, as well as a 300 minute call, then he stays on the phone for 1 minute, but does this a whole bunch of times? In other words, he could have made a 300+ minute call, then stayed on the phone for some x amount of time, let's say he accrued $20 in charges. Then he makes another 300+ min call, accruing another$20; such scenario would lead to multiple total minutes. Please help!

EDIT: Okay nevermind, I see now why the answer is B...
I misinterpreted the question as saying that anytime you exceed 300 mins of calling a new rate kicks in...and not that the new rate is rather applied in terms of total minutes...which totally makes sense because what kind of company designs a plan where the rate changes after 300 mins on the phone...

Still, when you're speeding through the GMAT and your mind is in critical/nit-pick mode for every single detail, it's easy to construe the words in such way. The question as written can easily be read to say that the 7 cent rate applies to the first 300 mins of calling time, and the new rate kicks in after.

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14 Apr 2017, 12:28
hsbinfy wrote:
C for me

1)gives time for .07 minute call .he talked for amount 21$=300 minutes.not suff(no inf about 0.05 call) 2) 40$ for 0.05 call i.e 800 minutes.not suff(no info about 0.07 call)

C-total of 1100 minutes

2) Because 2 tells you the cost of the calls charged at $0.05/min, you can deduce that the first 300 minutes of calling time at$0.07/min was used up. Therefore, 2) is suff. B

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Re: Last month a phone company charged $0 .07 [#permalink] ### Show Tags 14 Apr 2017, 18:07 chetan2u wrote: Skywalker18 wrote: Last month a phone company charged$ 0.07 per minute for the first 300 minutes of calling time and $0.05 per minute for each minute of calling time in excess of the first 300 minutes . For how many minutes of calling time was Bob charged by the phone company last month? 1) Last month the phone company charged Bob$21.00 for his calling time that was charged at $0.07 per minute. 2) Last month the phone company charged Bob$40.00 for his calling time that was charged at $0.05 per minute. Hi hsbinfy and manishpatwal, ans should not be C or D, it should be B.. the Q tells you.. first 300 = 0.07 per minute after 300 = 0.05 per minute.. we have to find TOTAL time.. lets see the statements- 1) Last month the phone company charged Bob$21.00 for his calling time that was charged at $0.07 per minute. we do not anything about the minutes beyond 300.. Insuff 2) Last month the phone company charged Bob$40.00 for his calling time that was charged at $0.05 per minute We know now how many minutes did he speak in excess of 300 =$$\frac{40}{0.05}= 800$$ minutes.. ans = 300+800 = 1100 Suff B chetan2u i have little difficulty understanding how B is correct how do you know$40 was counted over a single phone call
option B states the charge @0.05 for the entire month
so there might be chances he used 2*$20=$40 for entire month
then total may be = 300+ 300+ 800= 1400

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Last month a phone company charged $0 .07 [#permalink] ### Show Tags 19 Apr 2017, 09:41 rohit8865 wrote: chetan2u wrote: Skywalker18 wrote: Last month a phone company charged$ 0.07 per minute for the first 300 minutes of calling time and $0.05 per minute for each minute of calling time in excess of the first 300 minutes . For how many minutes of calling time was Bob charged by the phone company last month? 1) Last month the phone company charged Bob$21.00 for his calling time that was charged at $0.07 per minute. 2) Last month the phone company charged Bob$40.00 for his calling time that was charged at $0.05 per minute. Hi hsbinfy and manishpatwal, ans should not be C or D, it should be B.. the Q tells you.. first 300 = 0.07 per minute after 300 = 0.05 per minute.. we have to find TOTAL time.. lets see the statements- 1) Last month the phone company charged Bob$21.00 for his calling time that was charged at $0.07 per minute. we do not anything about the minutes beyond 300.. Insuff 2) Last month the phone company charged Bob$40.00 for his calling time that was charged at $0.05 per minute We know now how many minutes did he speak in excess of 300 =$$\frac{40}{0.05}= 800$$ minutes.. ans = 300+800 = 1100 Suff B chetan2u i have little difficulty understanding how B is correct how do you know$40 was counted over a single phone call
option B states the charge @0.05 for the entire month
so there might be chances he used 2*$20=$40 for entire month
then total may be = 300+ 300+ 800= 1400

Hi, The best way to solve this question is to set the appropriate equation.

Here, let X = the total time spent on the phone.

Thus you have the equation:

TOTAL CHARGE = .07(300) + .05(X-300) --> TOTAL CHARGE = 21 + .05X - 15
Where the $21 derives from the .07 cost per minute. And the .05x - 15 derives from the .05 cost per minute after the 300. Statement 1 Last month the phone company charged Bob$21.00 for his calling time that was charged at $0.07 per minute. Insufficient because we don't know about the second part of the charge, and additionally, this is information we already know. Statement 2 Last month the phone company charged Bob$40.00 for his calling time that was charged at $0.05 per minute. Sufficient because this tells us that .05X - 15 = 40. Therefore we can solve for X and get the answer. B. Kudos [?]: 13 [0], given: 194 Intern Joined: 30 Jun 2017 Posts: 1 Kudos [?]: 0 [0], given: 0 Re: Last month a phone company charged$ 0 .07 [#permalink]

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30 Jun 2017, 01:30
I understand the reason why the answer should be B but I think the question is misleading.

For instance based on statement 1 what if Bob made exactly 300 minutes of call in the last month? If the statement says he was charged >$21 then we can say it's not sufficient however we are told he was charged$21 dollars for calls he made last month which means he only made calls to 300 minutes.

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