When a man travels equal distances at speeds of V1 and V2 km/h, his average speed is 5 km/h. But when he travels at these speeds for equal time periods, his average speed is 5.5 km/h. Find the positive difference between the two speeds.

Question

Question

This question was previously asked in

RRB Group D 20 Sept 2022 Shift 1 Official Paper

Answer 1

Calculations:

According to question,

When distance is same

2V₁V₂/(V₁+ V₂) = 5 -----------(1)

When time interval is same

(V1 + V2)/2 = 5.5---------------(2)

⇒ (V1 + V2) = 11

On putting equation (2) in (1), we get:

V₁V₂/5.5 = 5

⇒V1V2 = 27.5

Now, (V1 - V2)

= √{(V1 + V2)² - 4V1V2 }

= √(121 - 110)

= √11

Hence, The Required value is √11.

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