66. A student takes a ten-question true-false quiz, but did not study and randomly guesses each answer.

Find the probability that the student passes the quiz with a grade of at least 70% of the questions correct.

Identify

First find the number of correct questions needed to get 70%.

Then write an appropriate probability statement.

Then find the probability

70. Suppose that about 85% of graduating students attend their graduation. A group of 22 graduating students is randomly chosen.

1. In words, define the random variableX.

2. List the values thatXmay take on.

3. Give the distribution ofX. X~(,)

4. How many are expected to attend their graduation?

5. Find the probability that 17 or 18 attend.

6. Based on numerical values, would you be surprised if all 22 attended graduation? Justify your answer numerically.