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A truck left 8 hours early than the scheduled time and in order to reach its destination 600 km away on time, it had to decrease its usual…

3424Medium DSSSB TGT Computer Science 0 replies

A truck left 8 hours early than the scheduled time and in order to reach its destination 600 km away on time, it had to decrease its usual speed by 20 km/hr. What is the usual speed of the truck?

A30 km/hr
B50 km/hr
C40 km/hr
D60 km/hr

Correct answer: B

Explanation

Let usual speed = v km/hr. 600/(v − 20) − 600/v = 8 gives v² − 20v − 1500 = 0, so v = 50 km/hr.

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