Homework Help: Probability

Posted by Alia on Friday, January 4, 2013 at 9:28pm.

If X is a normal random variable with mean 11, and if the probability that X is less than 12.10 is .72 , then what is the standard deviation of X?
Select one:
a. 3.00
b. 6.25
c. 2.50
d. 1.25

Please note that the answer for the above is stated as c.2.50. However, my answer comes to 1.89 which is not given as an option and I can't figure out where I'm going wrong so please can anyone help me with this problem.

Thanks.

Probability - MathMate, Saturday, January 5, 2013 at 12:07pm
I get 1.89 also.
Not sure if there is a typo or I made a mistake.

Answer this Question

Related Questions

Statistics - Suppose that the probability distribution of a random variable x ...
Statistics & Probability - If X is a normal random variable with mean 11, ...
probability - A random experiment of tossing a die twice is performed. Random ...
Statistics - Suppose that the probability distribution of a random variable x ...
statistics - Suppose that large dogs weights are normally distributed with a ...
Probability and statistics - 8. A random variable X takes exactly the 5 values 1...
math - let the random variable x denote the number of girls in a five-child ...
statistics - 1. A random sample of n = 16 scores is selected from a normal ...
statistics - A random sample of n= 16 scores is selected from a normal ...
Statistics and Probability - A computer supply house receives a large shipment ...

For Further Reading

First Name:
School Subject:
Answer: