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A car travels for 45 minutes at a speed of 80 km/h, the next 40 minutes at a speed of 48 km/h and the next 35 minutes at a speed of x km/h.…

3625Medium DSSSB TGT Computer Science 0 replies

A car travels for 45 minutes at a speed of 80 km/h, the next 40 minutes at a speed of 48 km/h and the next 35 minutes at a speed of x km/h. If his average speed for the whole journey is 72¹⁄₄ km/h, then what is the value of x ?

Correct answer: B

Explanation

Total time = 120 min = 2 h, so total distance = 72.25 × 2 = 144.5 km. Distances: 80 × 45/60 = 60 km and 48 × 40/60 = 32 km. So 35x/60 = 144.5 − 92 = 52.5 and x = 90 km/h.

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