12. A random sample of 40 students in various statistics courses had a mean test score of 86.5 with a standard deviation of 12.1 on their first exam. Construct the 90% confidence interval for the population mean test score on the first exam, . 13. Given the same sample statistics, which level of confidence will produce the widest confidence interval? A) 95% B) 90% C) 85% D) 75%

For the following questions, circle your answer and show all work. Solutions without work or reasoning may not receive credit. If you use a calculator, please write the function used. For example "binomcdf(10,0.5,5)" or "normalcdf(-E99,10,25,2)". If you use a formula and table, please show the formula or any calculations used.

Use the following to answer questions 14 - 18.

The normal distribution with mean 5.9 and standard deviation 3.6 is a good description of the Iowa Test Vocabulary scores of seventh grade students in Indiana. Let the random variable x represent the Iowa test score of a randomly selected Indiana seventh grader.

14. What is the probability the chosen student has a score of 7 or higher? 15. What is the probability the chosen student has a score between 3 and 6? 16. What is the probability the chosen student has a score lower than 5? 17. What Iowa test score represents the 1st quartile? 18. 10% of test scores are greater than ______.