header bg

Scan QR code or get instant email to install app


An educational institute that provides classes for the CFA exam has two batches enrolled for the June 2010 exam. Historically it has been observed that 69% of the candidates enroll in the weekday batch, while the remaining 31% prefer the weekend batch. The historical pass rate for the weekday batch has been 52%, and has been 63% for the weekend batch. Given that a student failed the exam, the probability that she was from the weekend batch is closest to:

A 25.72%.

1212This question requires us to use Bayes’ Formula for updated probability.
We have to find P (weekend |failure).
We are given the following information:
P (weekday) = 0.69
P (weekend) = 0.31
P (pass| week day) = 0.52
P (pass| weekend) = 0.63
We can infer the following:
P (fail| week day) = 1 − P (pass| weekday) = 1 – 0.52 = 0.48
P (fail| weekend) = 1 – P (pass| weekend) = 1 − 0.63 = 0.37
P (fail)= P(fail| weekday) x P (weekday) +P(fail| weekend) x P(weekend)= (0.48)(0.69) + (0.37)(0.31) = 0.4459
P (weekend| fail)= or 25.72%


Leave a Reply

Your email address will not be published.