If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

Bayes' theorem


There is a 80% chance that Ashish takes bus to the school and there is a 20% chance that his father drops him to school.
The probability that he is late to school is 0.5 if he takes the bus and 0.2 if his father drops him.
On a given day, Ashish is late to school.
Find the probability that his father dropped him to school on that day.
Express your answer as a number, rounded to two decimal places.
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi