- Assume that Z is a normal random variable with mean 0 and variance 1.
If someone can show either one of these I will be able to work the other I am confident.
2. A random variable has a normal distribution with μ=62.4. Find its standard deviation if the probability is 0.20 that it will take on a value greater than 79.2.
everytime I work this one out I get a negative SD. Basically hat i did was take the Z score from the table forthe 20% which was -.96. Then did the z= x-u/SD and re arranged to find it. 79.2-62.4/-.96 is a negative SD and not possible. I dont see what I am doing wrong.
3. A safety supervisor feels that 30% of all industrial accidents in his plant are caused by failure of employees to follow instructions. If this failure is correct, find approximately the probability that among 84 industrial accidents in his plant anywhere from 20 to 30 (inclusive) will be due to failure of employees to follow instructions.
Way lost on this one.
Thanks in advance guys, just a navy fella trying to get through some college and remember some of the basics.