Question

Sixteen percent of drivers registered in New Jersey are black. Of the 324 speeding tickets issued in one month on the NJ Turnpike, 25% went to black drivers. Is the percentage of speeding tickets issued to blacks unusually high compared with the state's registration information? Use the alpha = 0.05 level of significance

Answer 1

Solution :

This is the right tailed test .

The null and alternative hypothesis is

H0 : p = 0.16

Ha : p > 0.16

= 0.25

n = 324

P0 = 0.16

1 - P0 = -1 -0.16 = 0.84

Test statistic = z

= - P0 / [P0 * (1 - P0 ) / n]

=0. 25 -0.16 / [0.16*(0.84) /324 ]

= 4.419

P(z > 4.419) = 1 - P(z < 4.419) = 0

P-value = 0.0000

= 0.05

0 < 0.05

Reject the null hypothesis .

There is sufficient evidence to suggest that the percentage of speeding tickets issued to blacks unusually high compared with the state's registration information .