Suppose X is normally distributed with mean 100 and standard deviation 20.Without using tables,determine the approximate value of P(80

Question

Suppose X is normally distributed with mean 100 and standard deviation 20.Without using tables,determine the approximate value of P(80 < X < 100).
A) 0.997
B) 0.95
C) 0.68
D) 0.50
E) 0.34

Quizplus · Accepted Answer

The interval from 80 to 100 is one standard deviation below the mean (100 - 20 = 80). In a normal distribution, approximately 68% of the data falls within one standard deviation of the mean, so half of this (34%) is between the mean and one standard deviation below the mean.

Suppose X Is Normally Distributed with Mean 100 and Standard