# GRE® Quant Practice | Rates Q2

#### GRE Sample Questions | Average Speed Formula

The GRE maths sample question given below is a time and speed question from Rates. This GRE sample question helps you understand the concept of computing Average Speed.

Question 2: Sam covers the first 40% of the distance between two cities A and B at 50 kmph and the remaining distance at a speed of 75 kmph. What is his average speed for the entire travel?

1. 62.5 kmph
2. 65 kmph
3. 60 kmph
4. 66.66 kmph
5. 58.33 kmph

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### Explanatory Answer | GRE Time Speed Distance Q2

#### Given Data: Speeds for the first and the second part of journey

Speed for the first 40% of the distance = 50 kmph
Speed for the remaining 60% of the distance = 75 kmph

Average Speed Formula
Average Speed = $$frac{\text{Total Distance}}{\text{Total Speed}}$ What is the total distance ? The question stem has not provided the total distance of travel. The quickest way to solve the question is to assume a value for the distance. To compute the time taken we will divide the distance by speed. So, it makes sense to assume such a value for distance that is divisible by both 50 and 75 so that the results will be integers. So, the value that we assume for distance should be a multiple of 50 and a multiple of 75. i.e., it should be a common multiple of 50 and 75. The smallest common multiple is the LCM of$50, 75).
LCM (50, 75) = 150

Let 40% of the distance be 150 km.
∴ 60% of the distance = $$frac{60}{40}$ × 150 = $\frac{30}{2}$ × 150 = 225 km Part Speed Distance Time Taken First 40% 50 kmph 150 km $\frac{150}{50}$ = 3 hours Remaining 60% 75 kmph 225 km $\frac{225}{75}$ = 3 hours Total 375 km 6 hours Average Speed = $\frac{375}{6}$ = 62.5 kmph #### Choice A is the correct answer #### GRE Online Course - QuantTry it free! Register in 2 easy steps and Start learning in 5 minutes! #### Already have an Account? #### GRE Live Online Classes Next Batch August 26, 2022 ## Additional Practice Questions in Rates | Time Speed Distance & Work Time Pipes Cisterns ##### Where is Wizako located? Wizako - GMAT, GRE, SAT Prep An Ascent Education Initiative 14B/1 Dr Thirumurthy Nagar 1st Street Nungambakkam Chennai 600 034. India Work @ Wizako ##### How to reach Wizako? Mobile:$91) 93800 48484
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