# Normal distibution.

• May 26th 2011, 01:26 PM
Taylo17
Normal distibution.
A pizza place offers 3 different cheeses and 12 different toppings. In how many ways can a pizza be made with 1 cheese and 3 toppings?
A.198
B.660
C.1485
D.2376

The time required to finish a test in normally distributed with a mean of 40 minutes and a standard deviation of 8 minutes. What is the probability that a student chosen at random will finish the test in more than 56 minutes?
A.84%
B.2%
C.34%
D.16%

What percentage of the data falls within 1 standard deviation of the mean?
A.68%
B.95%
C.99%
D.100%
• May 26th 2011, 01:37 PM
pickslides
Quote:

Originally Posted by Taylo17
A pizza place offers 3 different cheeses and 12 different toppings. In how many ways can a pizza be made with 1 cheese and 3 toppings?
A.198
B.660
C.1485
D.2376

Consider $\displaystyle \displaystyle ^3C_1$ and $\displaystyle \displaystyle ^{12}C_3$

Quote:

Originally Posted by Taylo17

The time required to finish a test in normally distributed with a mean of 40 minutes and a standard deviation of 8 minutes. What is the probability that a student chosen at random will finish the test in more than 56 minutes?
A.84%
B.2%
C.34%
D.16%

$\displaystyle \displaystyle \mu = 40 , \sigma = 8 , x=56$

$\displaystyle \displaystyle z = \frac{x-\mu}{\sigma}$

What do you get?

Now find $\displaystyle \displaystyle P(Z>a)$

where 'a' is the result you found.

Quote:

Originally Posted by Taylo17
What percentage of the data falls within 1 standard deviation of the mean?
A.68%
B.95%
C.99%
D.100%

There is no working to be done here, this is information your text book should provide.