What is the lower and upper 90% confidence interval???

[jfb]

The scores on an examination in psychology are approximately normally distributed with mean 500 and an unknown standard deviation. The following is a random sample of scores from this examination.
432, 461, 475, 535, 560, 587, 641

Find a 90% confidence interval for the population standard deviation. Then complete the table below.
Carry your intermediate computations to at least three decimal places. Round your answers to at least two decimal places.

What is the lower limit of the 90% confidence interval?
What is the higher limit of the 90% confidence interval?

 

[tkhunny]

I never will understand the simple copying of the question to the board.

Please show your work. This is not a diffuclt problem if you have been paying attention in class at all. Please demonstrate that you have some course materials and have at least opened them.