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# If Alice traveled on a 10 km trip at a constant speed of 25 km/h and a

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Math Revolution GMAT Instructor
Joined: 16 Aug 2015
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If Alice traveled on a 10 km trip at a constant speed of 25 km/h and a  [#permalink]

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29 Jun 2018, 01:19
00:00

Difficulty:

15% (low)

Question Stats:

83% (01:24) correct 17% (02:04) wrong based on 52 sessions

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[GMAT math practice question]

If Alice traveled on a 10 km trip at a constant speed of 25 km/h and a 48 km trip at a constant speed of 30 km/h, what was her average speed, in kilometers per hour, for the two trips?

A. 26 km/h
B. 28 km/h
C. 29 km/h
D. 30 km/h
E. 32 km/h

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"Only $99 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Math Expert Joined: 02 Aug 2009 Posts: 6792 Re: If Alice traveled on a 10 km trip at a constant speed of 25 km/h and a [#permalink] ### Show Tags 29 Jun 2018, 03:29 1 MathRevolution wrote: [GMAT math practice question] If Alice traveled on a 10 km trip at a constant speed of 25 km/h and a 48 km trip at a constant speed of 30 km/h, what was her average speed, in kilometers per hour, for the two trips? A. 26 km/h B. 28 km/h C. 29 km/h D. 30 km/h E. 32 km/h Total distance traveled = 10+48=58 Time taken = $$\frac{10}{25}+\frac{48}{30}=2/5 + 8/5=2$$ Speed = 58/2=29 km/h C _________________ 1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372 2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html 3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html GMAT online Tutor Senior Manager Joined: 04 Aug 2010 Posts: 272 Schools: Dartmouth College If Alice traveled on a 10 km trip at a constant speed of 25 km/h and a [#permalink] ### Show Tags 29 Jun 2018, 03:54 1 MathRevolution wrote: [GMAT math practice question] If Alice traveled on a 10 km trip at a constant speed of 25 km/h and a 48 km trip at a constant speed of 30 km/h, what was her average speed, in kilometers per hour, for the two trips? A. 26 km/h B. 28 km/h C. 29 km/h D. 30 km/h E. 32 km/h Since Alice travels only a small portion of the total distance at 25 kph but the vast majority of the distance at 30 kph, her average speed for the entire trip must be just a bit less than 30 kph. Of the five answer choices, only C is sufficiently close to 30 kph. _________________ GMAT and GRE Tutor Over 1800 followers Click here to learn more GMATGuruNY@gmail.com New York, NY If you find one of my posts helpful, please take a moment to click on the "Kudos" icon. Available for tutoring in NYC and long-distance. For more information, please email me at GMATGuruNY@gmail.com. Senior SC Moderator Joined: 22 May 2016 Posts: 1977 If Alice traveled on a 10 km trip at a constant speed of 25 km/h and a [#permalink] ### Show Tags 29 Jun 2018, 13:07 MathRevolution wrote: [GMAT math practice question] If Alice traveled on a 10 km trip at a constant speed of 25 km/h and a 48 km trip at a constant speed of 30 km/h, what was her average speed, in kilometers per hour, for the two trips? A. 26 km/h B. 28 km/h C. 29 km/h D. 30 km/h E. 32 km/h Average speed = $$\frac{TotalDistance}{TotalTime}$$ Trip 1, time, $$T=\frac{D}{r}$$ $$T=\frac{10mi}{25mph}=\frac{2}{5}$$ hour Trip 2, time, $$T=\frac{48mi}{30mph}=\frac{8}{5}$$hour Total distance: (10 + 48) = 58 miles Total time: $$(\frac{2}{5}+\frac{8}{5})hrs=\frac{10}{5}hrs=2hrs$$ Ave. speed = $$\frac{TotalD}{TotalT}=\frac{58mi}{2hr}=29$$ mph Answer C _________________ In the depths of winter, I finally learned that within me there lay an invincible summer. -- Albert Camus, "Return to Tipasa" Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6219 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: If Alice traveled on a 10 km trip at a constant speed of 25 km/h and a [#permalink] ### Show Tags 01 Jul 2018, 18:14 => The total time taken for the two trips is $$\frac{10}{25} + \frac{48}{30} = 0.4 + 1.6 = 2$$ hours. The total distance traveled on the two trips is $$10 + 48 = 58 km.$$ Thus, the average speed for the two trips is the total distance over the total time, or $$\frac{58}{2} = 29 km / h.$$ Therefore, the answer is C. Answer: C _________________ MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. "Only$99 for 3 month Online Course"
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Re: If Alice traveled on a 10 km trip at a constant speed of 25 km/h and a &nbs [#permalink] 01 Jul 2018, 18:14
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