18.) (1 point) Here are the IQ test scores of 31 seventh-grade girls in a Midwest school district:

114

100

104

89

102

91

114

114

103

105

108

130

120

132

111

128

118

119

86

72

111

103

74

112

107

103

98

96

112

112

93

These 31 girls are an SRS of all seventh-grade girls in the school district. Suppose that the standard deviation of IQ scores in this population is known to be= 15. We expect the distribution of IQ scores to be close to Normal. Estimate the mean IQ score for all seventh-grade girls in the school district, using a 90% confidence interval.

to

19.)(1 point) It is known that the amount of time needed to change the oil on a car is normally distributed with a standard deviation of 5 minutes. A random sample of 80 oil changes yielded a sample mean of 28 minutes. Compute the 94% confidence interval estimate for the population mean.

Note:For each confidence interval, enter your answer in the form (LCL, UCL). You must include the parentheses and the comma between the confidence limits.

Confidence Interval =