SarkariPYQ

SSC GD 2023 PYQ — Question 58

SSC GD Constable (English) - 6 Feb 2023 - Shift 4 • Quantitative Aptitude • Q58

Back to paper

A motor-cycle covers 50 km with a speed of 25 km/hr. What must be the speed of the motor-cycle for the next 50 km journey so that the average speed of the whole journey is 30 km/hr ?

Show answer & explanation

Correct answer: C

Explanation

The correct answer is Option 3 i.e.  371237\frac{1}{2} km/hr.

Average speed = (2 × x × y)/(x + y)

here, x = 25 km/hr and y = ?

⇒ 30 = (2 × 25 × y)/(25 + y)

⇒ 30(25 + y) = 50 × y

⇒ 3(25 + y) = 5 × y

⇒ 75 + 3y = 5y

⇒ 2y = 75

⇒ y = 37.5 or 371237\frac{1}{2}