Question

Suppose that the average and standard deviation of the fine for speeding on a particular highway are 111.01 and 19.72, respectively. Calculate an interval that is symmetric around the mean such that it contains approximately 68% of fines. Assume that the fine amount has a normal distribution.

1)	(111.01, 19.72)

2)	(130.73, 91.29)

3)	(91.29, 130.73)

4)	(71.57, 150.45)

5)	(150.45, 71.57)

Answer 1

Solution :

Given that,

mean = = 111.01

standard deviation = = 19.72

Using Empirical rule,

a) P( - < x <   + ) = 68%

= P( 111.01 - 19.72 < x < 111.01 + 19.72 ) = 68%

= P( 91.29 < x < 130.73 ) =68%

3) ( 91.29, 130.73 )