Need help with practice questions.

A person interested in running for public office conducted a simple random sample to estimate the true proportion of voters who would vote for them. They selected 320 people and 6. 140 said they would vote for them on Election Day. Construct a 95% confidence interval to estimate the true proportion. A. (0.242, 0.326) B. (0.383, 0.492) C. (0.339, 0.461) D. (0.423, 0.513) E. (0.622, 0.899) 7. A random sample of the houses in a particular city is selected and the level of radon gas is measured for each house in the sample. The values collected are given below in parts per million (ppm). Experience has shown that radon gas level is approximately normally distributed for this population. . 4 8 13 6 7 3 9 8 11 8 Construct a 99% confidence to estimate the true mean level of radon in the city. A. (6.497, 8.903) B. (2.135, 13.265) C. (5.256, 10.144) D. (1.953, 13.447) F . (4.634, 10.766) 7. A statistical consulting firm is interested in performing a 99% confidence interval to estimate the average number of missed days of Seminole county workers last year. Assume o = 12 days. The firm wants the margin of error to be no bigger than 4 points. What's the minimum number of subjects that need to be selected to guarantee these results? A. 27 B. 60 C . 93 D . 121 8 . The mean of all IQ scores is 100 with a standard deviation of 15. A person takes the IQ test and is told they scored in the 95th percentile (they scored higher than 95% of all other test takers). What was the person's IQ score? The distribution of IQ scores is known to be approximately normally distributed. B. 120 C. 125 D. 130 E. 135