Question

A and B started simultaneously towards each other from places X and Y, respectively. After meeting at point M on the way, A and B took 3.2 hours and 7.2 hours, to reach Y and X, respectively. Then how much time (in hours) they take to reach point M?

• A. 4.8
• B. 5
• C. 4
• D. 5.2

Answer 1

Answer:

A. 4.8

Solution: Given: A and B are moving towards each other from places X and Y After meeting at point M they reach each other's starting points X and Y in 3.2 hours and 7.2 hours. Formula: S1 : S2 = √(T2/T1) S1 = Speed of car A, S2 = Speed of car B T1 = Time taken by car A to cover distance T2 = Time taken by car B to cover distance Concept: In relative speed when both objects come to each other their speed becomes the sum of their speed. Calculation: Let T be the time taken by them to reach point M. S1 : S2 = √(7.2/3.2) = 3 : 2 Let the ratio constant be x then S1 = 3x and S2 = 2x So, T = {(2x × 7.2) + (3x × 3.2)}/(3x + 2x) hours ⇒ T = (14.4x + 9.6x)/5x hours ⇒ T = 24x/5x = 4.8 hours ∴ The time taken by them to reach point M was 4.8 hours.