Question

A quiz consists of 100 multiple choice questions. Each question has 4 possible answers (A-D) and only one answer is correct. If the student guesses the answer to the questions, then what is the probability earn a grade of 70% or higher? Show how to on Ti-84 Calculator

Answer 1

This is Binomial probability problem with n = 100 , independent trials and p = 1 / 4

To earn grade 70% or higher , student need to get 70 or more answers correct.

We have to find P( x >= 70 )

P( x >= 70 ) = 1 - P( x <= 69 )

Using TI-84 , Let's find P( x <= 69 )

Steps : 2ND ---> STAT ----> Binomcdf ----> hit enter

Enter trials = 100 , p = 1/4 , x = 69 ----> Hit Enter.

We get , P( x <= 69 ) = 1

So, P( x >= 70 ) = 1 - 1 = 0

The probability earn a grade of 70% or higher is 0