A schoolboy wakes up late on average of 3 days in every 5 days. If he wakes up late, the probability that he is late for school is 9/10 . If he does not wake

P(get to school on time)

= 1 - P(late for school)

= $1- \left(\dfrac{3}{5}\times \dfrac{9}{10}+\dfrac{2}{5}\times \dfrac{3}{10}\right)\\ $

= 17/50

Therefore percentage of days he gets to school on time is 17/50 x 100% = 34%

A schoolboy wakes up late on average of 3 days in every 5 days. If he wakes up late, the probability that he is late for school is 9/10 . If he does not wake up late, the probability that he's late for school is 3/10 . On what percentage of days does he get to school on time?