Question

A man reaches his office 10 minutes late if he drives his car at 40 kmph, and 5 minutes early if he drives his car at 50 kmph from his home. How should I calculate the distance of his office from his home?

• A. 25
• B. 50
• C. 75
• D. 100

Answer 1

Answer: (B)

50

Answer 2

Speed $=\frac{distance}{time}$

40 $=\frac{distance}{(t+10)}$

50 $=\frac{distance}{(t-5)}$

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

4t + 40 = 5t - 25
t = 65 min
distance = speed $\times$ time

= 40 $\times$ $(\frac{75}{60})$ --- in hours
= 50 km
So the correct option is (B)