# Confidence Intervals.

• Nov 14th 2012, 09:17 AM
JabberJayy
Confidence Intervals.
A random sample of 20 phials was drawn from a large consignment. The volume of the phails was known to be normally distributed with standard deviation α= 1.566ml. The sample mean was calculated to be 4.891ml. Construct the 99% confidence limits for the mean volume of the phails in the consignment?

Can anyone please help me? my tutor is actually useless and makes everything so complicated.
• Nov 14th 2012, 12:30 PM
abender
Re: Confidence Intervals.
Quote:

Originally Posted by JabberJayy
A random sample of 20 phials was drawn from a large consignment. The volume of the phails was known to be normally distributed with standard deviation α= 1.566ml. The sample mean was calculated to be 4.891ml. Construct the 99% confidence limits for the mean volume of the phails in the consignment?

Can anyone please help me? my tutor is actually useless and makes everything so complicated.

Do you know how to read the chart of Z scores? Show us what you know.