Aptitude

Question

Walking at 4/5 of normal speed a man is 10 minute late.Find usual time in minutes

Comments

$\frac{v}{(4v)/5}$ = $\frac{t + 10}{t}$

Solving this, t = 40 min

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ok thanks :)

Answer 1

let distance covered is ...d and usual speed is v..

then usual time taken to travel d is...d/v

time taken to travel d distance with modified speed..

d/(4/5)v = d/v+10  ..d/v=40

Answer 2

new speed = 4/5 of normal speed

new time taken = 5/4 of normal time

 

so,  

5/4 of normal time  - (normal time ) = 10 minutes

1/4  of normal time =  normal time = 40 minutes

Answer 3

As, Speed ∝ 1/Time

&    Time ∝ 1/Speed

 S' (Present Speed) = S x 4/5

 T' (Present Time) = 1 / (Sx4/5)

                              = T x (5/4)   [ ∵T = 1/S]

∴ Present Time - Usual Time = 10

   T x (5/4) - T = 10

   (5T-4T)/4 = 10

    T = 10 x 4 =40

∴ Usual Time is 40 mins.