CH13-15 GROUP QUIZ

1) Two friends, Ty and Skya, take a quiz every week. From past experiences, it is known that both friends’ scores are approximately normally distributed, where Ty has a mean score of 90 with a standard deviation of 12, and Skya has a mean score of 85 with a standard deviation of 6. Assuming that their scores are independent, which of the following values is closest to the probability that Ty will have a lower score than Skya in a single quiz? A) 0.35B) 0.39C) 0.32D) 0.20E) None of theseA

A survey asks a random sample of 100 OHS students if they support an increase in game tickets with additional revenue covering expense of academic tutors for students involved in extra-curricular activities. Let X denote the number in the sample that say they support the increase. Suppose 40% of all students at OHS support the increase.2. The expected value (mean) of X is:

3) Mr. and Mrs. Garcia have each decided to provide extra credit points each week for the next 6 weeks. Suppose the amount of extra credit points provided in a week by Mr. Garcia is normally distributed with a mean of 5 points and a standard deviation of 1 point, and the amount of extra credit points provided in a week by Mrs. Garcia is normally distributed with a mean of 6 points and a standard deviation of 2 points. What is the expected number of weeks in a 6 week period that their combined extra credit will exceed 10 points? 2

4. The standard deviation of X is:

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- Calculus