Question

if i walk at 7/6 of my usual speed, then i reach my ofce 15 minutes early. What is the usual time taken (in minutes) by me to reach the ofce?

Answer 1

Answer:

105 minutes

Step-by-step explanation:

Let my usual speed of walking be v m/min and  my usual time taken to reach office be t minutes.

My new speed, v' = (7/6)v

New time taken to reach office, t' = (t-15) minutes.

We know that,

Distance = speed x time

Since  distance between my house and office is constant,

v x t = v' x t'

or vt = (7/6)v (t-15)

or vt = (7/6)vt - 35/2

or vt/6 = 35/2

or vt = 105

Thus, distance between my house and office is 105 metres

Now, difference in time taken to reach office, t-t' = 15 minutes

Thus, 105/v -  105/ (7/6)v = 15

or  1/v - 6/7v = 15/105

or 1/7v = 1/7

or v = 1 m/min

Thus, usual time taken

t = Distance/Usual speed

= 105/1 =  105 minutes

or Usual time taken to reach office = 105 minutes

Hope that helped you.

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