Question

An objectcovers 1st half of the distance at a speed of 40 km per hr and 2nd half at a speed of 60km per hr calculate its average speed

Answer 1

hey
here is ur answer
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let a = average speed for the trip
let d = half the distance
:
write a time equation, time = dist/speed

d/40 +d/60 =2d/a

we don't need d, divide thru by d and you have
1/40 +1/60 =2/a
multiply by 120a to clear the denominators, results:
3a + 2a = 120(2)
5a = 240
a = 240/5
a = 48 km/hr
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I hope this will help
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