GMAT Book 2: Rates - Races

Races is an extension of speed time distance. You could expect one question in the GMAT quant section testing ideas covered in this chapter. This topic tests the idea of people racing against each other, racing with a head start, dead finish and other related ideas.

Syllabus Covered in Wizako's GMAT Book - Races

The chapter on Races is essentially an extention to the concepts covered in the Speed Time and Distance Chapter and Ratio Proportion chapter. The lesson book has questions on two types of races - Races along a straight track and Circular Races. Wizako's GMAT Math Lesson Book in this chapter covers the following concepts:

1. Definition of the term race
2. Explanation of the concept of races along a straight track
3. Illustrative Examples to consolidate the idea
4. 8 solved examples are provided with detailed explanation for races along a straight track
5. The concept of race in a circular path is explained along with examples
6. 4 solved examples are given with detailed explanation
7. 13 exercise problem of both types of races with the answer key and explanatory answers
8. A multiple choice test with 26 GMAT level questions. Explanatory answers to all questions and an answer key are provided for the test.

Here is a typical solved example in Wizako's GMAT Book from this chapter

Sample Question

P and Q run around a circular track of radius 49 meters starting from the same point at the same time and in the same direction. If 'P' runs at a speed of 15 m/min and 'Q' runs at a speed of 10 m/min, when will they meet again for the first time?

Explanatory Answer

P and Q run in the same direction. Therefore, their relative speed = 15 - 10 = 5 m/min

Circumference of the circular track is the length of the circular track = 2πr
= 2 × \\frac{22}{7}) × 49 = 308 m.

Time taken for P and Q to meet for the first time after they have started a race along a circular track, starting simultaneously from the same point is
\\frac{\text{length of the circular track}}{\text{relative speed}}) = \\frac{308}{5}) = 61.6 minutes

61.6 minutes = (60 + 1 + 0.6) minutes = 1 hour, 1 minute and (0.6 × 60) seconds

Therefore, they will meet for the first time after 1 hour, 1 minute and 36 seconds.

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