A student takes an exam containing 18 true or false questions, if the students guesses, what is the probability that he will get less than 10 but more than 7 questions right

0.3523 is the probability that the student will get less than 10 but more than 7 questions right.      

Step-by-step explanation:

We are given the following information:

We treat answering the question correctly as a success.

P(guess of answer is correct) = 50% = 0.5

Then the number of questions follows a binomial distribution, where

where n is the total number of observations, x is the number of success, p is the probability of success.

Now, we are given n = 18

We have to evaluate:

0.3523 is the probability that the student will get less than 10 but more than 7 questions right.

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so:

1696 hundred thousand

step-by-step explanation: