Suppose that 15 children, who were learning to ride bikes, were surveyed to determine how long they had to use training wheels. It was revealed that they used them an average of 25 weeks with a sample standard deviation of 5 weeks.

1. Define Random variable X in words.

2. Define Random variable X in words.

3. Which distribution should you use for this problem? Explain your choice. 1

4. We want to construct 90% confidence interval for the population mean length of time for using training wheels. Answer the following:

(a) Find error bound for the mean.

(b) Construct the Confidence interval

(c) Explain what a 90% confidence interval means for this study