Out of 2000 random but normally distributed numbers with a mean of 45 and a standard deviation of x, approximately 1360 numbers are found to be between 40 and 50. What is the value of x?
First we have to find which percent of 2000 numbers are 1360 numbers. p = 1360 / 2000 * 100 = 68 % It means that for normal distribution the values 40 and 50 are within +/- 1 standard deviation from the mean ( 45 ). 45 - x = 40 and 45 + x = 50. x = 45 - 40 = 50 - 45 = 5 Answer: x = 5
