D Question 19 2 pts A random sample of 10,000 longleaf pine trees are measured for height in order to test the hypothesis that the average tree height is not equal to 70 feet. Assume the population height is normally distributed with a standard deviation of 8. The sample mean is found to be 70.6 feet. At a 0.05 level of significance, which of the following may we conclude about the mean height? The population has a larger standard deviation than 8 It is not significantly different from 70 The sample mean is higher than the true population mean It is significantly different from 70 Next Previous Not saved Submit QuizQuestion 17 2 pts A high school principal is interested in how many hours each student spends on homework each day. She collects a sample of 50 and finds a sample mean of 1.4. She constructs confidence intervals at the 95% level. The margin of error is 0.8. What is the width of the confidence interval? O 1.1 O 0.4 O 1.2 O 1.6 Next PreviousD Question 18 2 pts A random sample of 10,000 longleaf pine trees are measured for height in order to test the hypothesis that the average tree height is not equal to 70 feet. What should be the null and alternative hypotheses? Let be the population mean and let Xbar be the sample mean. O HO: Xbar = 70; HA: Xbar#70 O HO: Xbar#70; HA: Xbar=70 HO: H = 70; HA: H#70 O HO: H#70; HA: H=70 Next Previous Not saved Submit QuizD Question 16 2 pts The sample mean is 68, the population standard deviation is 15, and the confidence level is 90%. If we construct a confidence interval, what is the probability that it will NOT contain the population mean? 10% O 5% O 25% O 90% Next Previous Not saved Submit QuizD Question 20 2 pts A researcher constructs a hypothesis test where the null hypothesis is u s O and alternative is u > 0. She finds a sample mean of 112 from a sample size of 16. Assume the population standard deviation is 400 and a significance level of 0.05. What should she do? Reject the null hypothesis O Fail to reject the alternative hypothesis O Accept that the mean is significantly different from 0 O Fail to reject the null hypothesis Next Previous Not saved Submit Quiz