# Revision For Exams

3 Questions  Settings  This is an exam question of confidence intervals

Related Topics
• 1.
Achievement Questions 1.   A survey is carried out to determine the amount of time children spend watching television each week. A random sample of 200 children gave an average time of 38.6 hours with a standard deviation of 8.4 hours. a)      Calculate the standard error of the mean. This is found by theta over root n = 0.544
• A.

True

• B.

False

• 2.
1.   A survey is carried out to determine the amount of time children spend watching television each week. A random sample of 200 children gave an average time of 38.6 hours with a standard deviation of 8.4 hours.b)  Find a 95% confidence interval for the mean number of hours of television watched by all children.
• A.

B) CI = 34.77 < mu < 45.34

• B.

B) CI = 37.44 < mu < 39.76

• C.

B) CI = 37.24 < mu < 39.47

• D.

B) CI = -7.24 < mu < 9.47

• 3.
2.   The viewing hours of adults are thought to average 21.7 hours with a standard deviation of 7.5 hours. A random survey of 350 adults gives a mean of 23.8 hours. Find a 90% confidence interval for the mean number of viewing hours for all adults.
• A.

A) CI = 23.14 < mu < 29.47

• B.

A) CI = -23.14 < mu < 39.47

• C.

A) CI = 23.14< mu < 29.96

• D.

A) CI = 23.14< mu < 29.96