### Normal Distribution- HELP

Posted:

**Sun Jul 07, 2013 6:02 pm**Questions:

1. random variable X normally distributed with mean 25.

The shaded region between 25 and 27 represents 30% of the distribution.

a). Find P(X>27)

b). Find the standard deviation of X

2. A random variable X is distributed normally with a mean of 20 and variance 9.

a). Find P(X<(or equal to)24.5)

b). Let P(X<(or equal to)k)=0.85

ii). Find the value of k.

So lost atm, tried so many different ways but I'm getting wrong answers- please help.

1. random variable X normally distributed with mean 25.

The shaded region between 25 and 27 represents 30% of the distribution.

a). Find P(X>27)

b). Find the standard deviation of X

2. A random variable X is distributed normally with a mean of 20 and variance 9.

a). Find P(X<(or equal to)24.5)

b). Let P(X<(or equal to)k)=0.85

ii). Find the value of k.

So lost atm, tried so many different ways but I'm getting wrong answers- please help.