Question

a person takes 20 minutes more to cover a certain distance as he increases his speed by 20%. the time taken to cover the distance at his original speed. i want clear explaination

Answer 1

let " t " minutes he take to covers the distance at original speed .
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so,
time = t = t minute

original speed = v = v

distance = S = S

we know ,

speed = distance/time

V = S/t

S = Vt ----------(1)
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final speed = V= 20%V = 20v/100

time = T = (t+20) minutes

distance = S ,(it should cover same distance)
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speed = distance/time

20V/100 = S/t+20

20V(t+20) = 100S

S = 2V(t+20)/10 -----------(2)
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from equation (1) and (2)

2v(t+20) = vt

2(t+20)/10 = t

2t + 40 = 10t

2t-10t = -40

-8t = -40

t = -40/-8

t = 5 minutes .
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so
your answer is , 5 minutes

That person take 5 minute to covers the certain distance at original speed " V "

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similarly ,
t+20 = 5+20 = 25 minutes
so he takes 25 minutes if he increase his speed 20%