A true/false test consists of 25 questions. A student knows the correct answer to 10 of the questions. She guesses each of the other answers independently based on the toss of a coin. a) Find the expectation of the number of correct answers.

The expectation of the number of correct answers is 17.5

Step-by-step explanation:

For each question, there are only two possible outcomes. Either the student guesses it correctly, or he does not. The probability of a student guessing the answer of a question correctly is independent of other questions. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

The expected value of the binomial distribution is:

In this problem, we have that:

25 questions.

The student know the answer for 10 questions. So for these 10 questions, p = 1.

On the other 25-10 = 15, she will guess, which there is one correct answer out of 2 options(true/false), so p = 1/2 = 0.5. So

The expectation of the number of correct answers is 17.5

dalila is incorrect. the whisker on the left is very long, going all the way out to 5. the whisker goes from 5 to 30, so it has a spread of 25. the rest of the box plot values are closer together, so 5 is an outlier

40 x 50 = 2000

step-by-step explanation: