# Math Help - Normal distibution.

1. ## 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%

2. 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 $\displaystyle ^3C_1$ and $\displaystyle ^{12}C_3$

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

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

What do you get?

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

where 'a' is the result you found.

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.