Question

A girl walks 12 km at the speed of 3 km/h. What change should she make in her speed to
take (i) an hour less and (ii) an hour more to cover the distance?
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Answer 1

Answer:

(i) 4 km/h

(ii)12/5 =2.4 km/h

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Answer 2

Answer:

Distance= 12km

Speed = 3km/h

Time= Distance / speed

T1 = 12/ 3 = 4hr

i) if a girl takes an hr less the speed becomes

T2 = T1 - 1 = 4 - 1 = 3 hr

speed = Distance / time

= 12 / 4 = 3 km/h

so the change in speed = 4km/hr - 3km/h= 1 km/

hr.

ii) an hr more to cover the distance

T3 = T1 + 1 = 4+ 1 = 5 hr

Speed becomes = distance / time

= 12 / 5 = 2.4 km/ hr.