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?

- 62.5 kmph
- 65 kmph
- 60 kmph
- 66.66 kmph
- 58.33 kmph

From INR 2999

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

Try it free!

Register in 2 easy steps and

Start learning in 5 minutes!

Copyrights © 2016 - 24 All Rights Reserved by Wizako.com - An Ascent Education Initiative.

Privacy Policy | Terms & Conditions

GMAT^{®} is a registered trademark of the Graduate Management Admission Council (GMAC). This website is not endorsed or approved by GMAC.

GRE^{®} is a registered trademarks of Educational Testing Service (ETS). This website is not endorsed or approved by ETS.

SAT^{®} is a registered trademark of the College Board, which was not involved in the production of, and does not endorse this product.

**Mobile:** (91) 93800 48484

**WhatsApp:** WhatsApp Now

**Email:** learn@wizako.com

Leave A Message