A hockey match is played from 3 pm. to 5 pm. A man arrives late for the match. What is the probability that he misses the only goal of the match which is scored at the 20^th minute of the match?

Dear student
The man can arrive anytime between 3pm to 5pm.
So, total duration = 2 hrs = 120 mins.
Now he sees the goal only if he arrives within first 20 mins.
So, Probability(he sees the goal) = $\frac{\mathrm{favourable} \mathrm{duration}}{\mathrm{total} \mathrm{duration}}= \frac{20 \mathrm{mins}}{120 \mathrm{mins} }= \frac{1}{6}$
Regards