posted by Student on .
Darby guesses the answers to six questions on the math portion of her college entrance exam. Each question is a true or false question. What is the approximate probability that at least 4 of her answers are correct?
The answer is
Here there are 6 questions, so n=6, and
there are 2^6=64 possible sets of answers.
Since 4 of them are right, the number of combinations with 4 correct out of 6 is
What would be the probability that 4 out of six are correct if the answers are completely random?