1. ## Probability

Hello everyone,

Hope you're all OK!

I was having trouble with a problem and was wondering if anyone could point me in the right direction. Thanks in advance

A prof. is creating a 20 question true or false quiz. They want to make sure that the probability of a student passing who guesses all the questions is less than 0.05. What should they make the passing grade?

2. Originally Posted by Slumzo
Hello everyone,

Hope you're all OK!

I was having trouble with a problem and was wondering if anyone could point me in the right direction. Thanks in advance

A prof. is creating a 20 question true or false quiz. They want to make sure that the probability of a student passing who guesses all the questions is less than 0.05. What should they make the passing grade?
Let X be the random variable number of correct guesses.

X ~ Binomial(n = 20, p = 1/2).

You require the smallest integer value of x such that $\Pr(X \geq x) < 0.05$

Using technology (TI-89) to guess-and-check I get x = 15.