SOLUTION: In a certain distribution of​ numbers, the mean is 90 with a standard deviation of 5. At least what fraction of the numbers are between 50 and 130​? At least (blank)

Algebra ->  Probability-and-statistics -> SOLUTION: In a certain distribution of​ numbers, the mean is 90 with a standard deviation of 5. At least what fraction of the numbers are between 50 and 130​? At least (blank)      Log On


   

Question 1116193: In a certain distribution of​ numbers, the mean is 90 with a standard deviation of 5. At least what fraction of the numbers are between 50 and 130​?
At least (blank) of all the numbers must lie between 50 and 130.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Calculate the z scores for both values.
z%5B1%5D=%2850-90%29%2F5=-8
z%5B2%5D=%28130-90%29%2F5=8
So then,
P=P%28z%5B2%5D%29-P%28z%5B1%5D%29
P=P%288%29-P%28-8%29
P=1-0
P=1
100%, up to 12 decimal places.