For 10-13, suppose the mean of the scores on an exam given to all tenth
graders at a school is 82.4 with a standard
deviation of 18.3. A random sample of 20
of the scores is chosen. Round answers to
the nearest tenth.
10. What interval captures 68% of the means
for random samples of 20 scores?
11. What is the probability that the sample
has a mean score of at most 75?
12 What is the probability that the sample
has a mean score of at most 85?
13. What is the probability that the sample
has a mean score between 73 and 87?
14. The mean time that students at a school
take to complete a test is 97 4 minutes
with a standard deviation of 14 5 minutes
A random sample of 25 of the times is
chosen Choose True or False for each
statement about the test.
A The interval 91.6 to 103 2 captures
95% of the means for random
samples of the times
O True False
B The probability that the sample has a
mean time over 100 minutes is
18.5%
O True False
C The probability that the sample has a
mean time at least 95 minutes is
16.6%
True False