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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## The price of a phone call consists of a standard connection tagged by: BTGmoderatorLU ##### This topic has 4 expert replies and 0 member replies ### Top Member ## The price of a phone call consists of a standard connection ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult Source: Manhattan Prep The price of a phone call consists of a standard connection fee, which is constant, plus a per minute charge. A 10-minute call costs$2.90 and a 16-minute call costs $4.40. How much does a 13-minute call cost? A.$3.55
B. $3.57 C.$3.58
D. $3.65 E.$3.77

The OA is D

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Hi All,

We're told that the price of a phone call consists of a standard connection fee, which is constant, plus a per minute charge, a 10-minute call costs $2.90 and a 16-minute call costs$4.40. We're asked for the cost of a 13-minute call. This question can be solved in a couple of different ways - and there's a great 'rate shortcut' that you can use to avoid some of the extra math that comes with certain approaches.

Since there's a standard connection fee, we know that the difference between the costs of two calls is solely due to the number of minutes in the call. With the given information (about a 10-minute call and a 16-minute call), the difference in price comes down to the 6 minute difference in the length of the calls. Thus, the extra 6 minutes cost an extra $4.40 -$2.90 = $1.50. We're asked for the cost of a 13-minute call - which is exactly 'halfway' between those two prices. Half of$1.50 is $0.75, so we can add that to the cost of a 10-minute call to find the cost of the 13-minute call.$2.90 + $0.75 =$3.65

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

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BTGmoderatorLU wrote:
Source: Manhattan Prep

The price of a phone call consists of a standard connection fee, which is constant, plus a per minute charge. A 10-minute call costs $2.90 and a 16-minute call costs$4.40. How much does a 13-minute call cost?

A. $3.55 B.$3.57
C. $3.58 D.$3.65
E. $3.77 Letting f = the standard connection fee and n = the per-minute charge, we can create two equations, one for the 10-minute call and one for the 16-minute call:: f + 10n = 2.90 and f + 16n = 4.40 Subtracting the first equation from the second, we have: 6n = 1.50 n = 0.25 Substituting 0.25 for n into the first equation, we see that f is: f + 2.5 = 2.90 f = 0.4 So a 13-minute call costs 0.4 + 13 x 0.25 =$3.65.

Alternate solution:

If we let m = the per-minute charge, x = the number of minutes, b = the standard connection fee, and y = the total cost of an x-minute call, we will have y = mx + b. As we can see, this is a line, and the ordered pairs (10, 2.90) and (16, 4.40) are on this line. We are looking for the y-value when x = 13. We can observe that 13 is exactly halfway between 10 and 16; therefore, the y-value should be exactly halfway between 2.90 and 4.40 also. Thus y = (2.90 + 4.40)/2 = 7.30/2 = 3.65.

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BTGmoderatorLU wrote:
Source: Manhattan Prep

The price of a phone call consists of a standard connection fee, which is constant, plus a per minute charge. A 10-minute call costs $2.90 and a 16-minute call costs$4.40. How much does a 13-minute call cost?

A. $3.55 B.$3.57
C. $3.58 D.$3.65
E. $3.77 $$? = f + 13c\,\,\,\,\left[ \ \right]$$ The constant fee (f) and the minute-charge (c) will be considered in CENTS. (Amounts in cents are always integers!) $$\left\{ \matrix{ \,f + 10c = 290 \hfill \cr \,f + 16c = 440 \hfill \cr} \right.\,\,\,\,\,\,\,\,\mathop \Rightarrow \limits^{\left( + \right)} \,\,\,\,\,\,2f + 26c = 290 + 440\,\,\,\,\,\,\mathop \Rightarrow \limits^{{\rm{focus}}\,!} \,\,\,\,\,\,? = {{2f + 26c} \over 2} = 145 + 220 = 365\,\,\,\,\,\,\left[ {\,{\rm{cents}}\,} \right]$$ This solution follows the notations and rationale taught in the GMATH method. Regards, Fabio. _________________ Fabio Skilnik :: GMATH method creator ( Math for the GMAT) English-speakers :: https://www.gmath.net Portuguese-speakers :: https://www.gmath.com.br Last edited by fskilnik@GMATH on Wed Oct 17, 2018 8:02 am; edited 1 time in total ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 12744 messages Followed by: 1247 members Upvotes: 5254 GMAT Score: 770 BTGmoderatorLU wrote: Source: Manhattan Prep The price of a phone call consists of a standard connection fee, which is constant, plus a per minute charge. A 10-minute call costs$2.90 and a 16-minute call costs $4.40. How much does a 13-minute call cost? A.$3.55
B. $3.57 C.$3.58
D. $3.65 E.$3.77

The OA is D
A 10-minute call costs $2.90 and a 16-minute call costs$4.40
$4.40 -$2.90 = $1.50, and 16 minutes - 10 minutes = 6 minutes So, the extra$1.50 paid for extra 6 minutes of calling
So, $0.75 would pay for 3 minutes of calling How much does a 13-minute call cost? A 10-minute call costs$2.90
So, the cost of a 13-minute call = $2.90 +$0.75 = $3.65 Answer: D Cheers, Brent _________________ Brent Hanneson – Creator of GMATPrepNow.com Use our video course along with Sign up for our free Question of the Day emails And check out all of our free resources GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months! • Free Trial & Practice Exam BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • 1 Hour Free BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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