Question

A student is taking a​ multiple-choice exam in which each question has two choices. Assuming that she has no knowledge of the correct answers to any of the​ questions, she has decided on a strategy in which she will place two balls​ (marked Upper A and Upper BA and B​) into a box. She randomly selects one ball for each question and replaces the ball in the box. The marking on the ball will determine her answer to the question. There are nine ​multiple-choice questions on the exam. Complete parts​ (a) through​ (d) below.

a. What is the probability that she will get nine questions​ correct?

b. what is the probability that she will get at least four questions correct?

(c) What is the probability that she will get no questions​ correct?

(d)What is the probability that she will get no more than two questions​ correct?

Answer 1

Here p=1/2=0.5 with is same for all, n=9 is constant, only two outcomes and events are independent

So all the properties of binomial are satisfied

Hence we will use excel formula of binomial to find required probabilities

a.

b.

c.

d.