# standard distribution. Help!

• Oct 21st 2009, 11:07 AM
Almondzqueen
standard distribution. Help!
The weights of certain hardcover books on a small shelf are normally distributed with a mean of 9.75g and a standard deviation of 0.08g. Find the weights that separate the top 5% and the bottom 5%.

So my answer looks like this:
z= x-u/σ
1.645 = x -9.75 -.08
1.645*.08 + 9.75 = 9.8816

Is this the answer? I have this class online and its hard to reach the teacher sometimes. I have a feeling this problem is incomplete. Can anyone enlighten me?(Speechless)
• Oct 21st 2009, 09:08 PM
mr fantastic
Quote:

Originally Posted by Almondzqueen
The weights of certain hardcover books on a small shelf are normally distributed with a mean of 9.75g and a standard deviation of 0.08g. Find the weights that separate the top 5% and the bottom 5%.

So my answer looks like this:
z= x-u/σ
1.645 = x -9.75 -.08
1.645*.08 + 9.75 = 9.8816

Is this the answer? I have this class online and its hard to reach the teacher sometimes. I have a feeling this problem is incomplete. Can anyone enlighten me?(Speechless)

You've found the weight that seperates the top 5%. Now you have to find the weight that seperates the bottom 5%.