walking at 3/5 of his usual speed a man reaches his office 40 min late find his usual time to reach the office in minute please explain me in detail

Question

walking at 3/5 of his usual speed a man reaches his office 40 min late find his usual time to reach the office in minute


please explain me in detail

Answer 1

Hi Amey,

 

Let's set this up.

 

r = usual speed

t = usual time

d = distance to office

 

3/5r = slower speed

t+40 = time when walking at slower speed

 

Since the distance to the office is a constant, i.e. does not change when walking faster or slower, we can say

 

rt = (3/5)r(t+40)

rt = (3/5)rt + 24r

 

Divide all terms, both sides by rt

 

rt/rt = (3/5)(rt)/(rt) + 24r/(rt)

1 = 3/5 + 24/t

2/5 = 24/t

t = 24/(2/5) = 24*5/2

t = 60 minutes

 

It usually takes him 60 minutes to reach the office.