Question

A test consists of ten true/false questions. A student who forgot to study guesses randomly. What is the probability that the student answers exactly five questions correctly?

Answer 1

252/1024

Explanation:

There are two possible answer choices for each question, meaning that there is a total of 2^10=1024 possible true-false combinations. There are
`{ 10 \choose 5 }= 252` possible ways to choose the 5 out of 10 to be correct. There is thus a 252/1024 chance to get exactly five correctly.