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0:35:59Question 18Not yet answeredMarked out of 6.00Flag questionTipsQUESTION 3PART 1A student is taking a multiple choice test consisting of five questions, each with four options for each question. The student selects the answers at random.a) What is the probability that the student will get at least one question correct?b) Calculate the expected number of questions correct.PART 2A sample of 100 people is selected for a survey, among the questions asked was"Do you like Statistics?" and "Do you live in Wollongong?". Of the 100 people,  80 said they like Statistics, 53 people said they like Statistics and also live in Wollongong(at the same time), 15 people said they don't like Statistics and also don't live in Wollongong (at the same time).a) Find the following probability, P(Likes Statistics | Live in Wollongong)b) Are the events "Likes Statistics" and "Lives in Wollongong" statistically independent?Show your working by typing your answer in the text box below.

Question

0:35:59Question 18Not yet answeredMarked out of 6.00Flag questionTipsQUESTION 3PART 1A student is taking a multiple choice test consisting of five questions, each with four options for each question. The student selects the answers at random.a) What is the probability that the student will get at least one question correct?b) Calculate the expected number of questions correct.PART 2A sample of 100 people is selected for a survey, among the questions asked was"Do you like Statistics?" and "Do you live in Wollongong?". Of the 100 people,  80 said they like Statistics, 53 people said they like Statistics and also live in Wollongong(at the same time), 15 people said they don't like Statistics and also don't live in Wollongong (at the same time).a) Find the following probability, P(Likes Statistics | Live in Wollongong)b) Are the events "Likes Statistics" and "Lives in Wollongong" statistically independent?Show your working by typing your answer in the text box below.

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Solution

PART 1

a) The probability of getting a question correct by guessing is 1/4 (since there are 4 options). The probability of getting a question wrong is therefore 1 - 1/4 = 3/4.

Since there are 5 questions, the probability of getting all questions wrong is (3/4)^5 = 0.2373.

The probability of getting at least one question correct is therefore 1 - the probability of getting all questions wrong = 1 - 0.2373 = 0.7627.

b) The expected number of questions correct is simply the probability of getting a question correct times the number of questions. So, 1/4 * 5 = 1.25.

PART 2

a) The probability of liking Statistics given that the person lives in Wollongong is the number of people who like Statistics and live in Wollongong divided by the total number of people who live in Wollongong.

We know that 53 people like Statistics and live in Wollongong, but we need to find out how many people live in Wollongong in total.

We know that 15 people don't like Statistics and don't live in Wollongong, so the number of people who live in Wollongong is 100 - 15 = 85.

So, P(Likes Statistics | Live in Wollongong) = 53/85 = 0.6235.

b) Two events are statistically independent if the probability of both events occurring is the product of the probabilities of each event occurring individually.

We know that P(Likes Statistics) = 80/100 = 0.8 and P(Lives in Wollongong) = 85/100 = 0.85.

The probability of both events occurring is 53/100 = 0.53.

Since 0.8 * 0.85 = 0.68, which is not equal to 0.53, the events are not statistically independent.

This problem has been solved

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