Question

The claim is that the standard deviation of the speeds of drivers in Bradford is 8 mph. An experienced driver feels that this is very low. If a random speed check is conducted for 50 drivers, the standard deviation is 10.5 mph. Can we reject the null at

Answer 1

Answer:

Null hypothesis is rejected. Standard deviation is > 8 miles per hour

Step-by-step explanation:

σ [Population standard deviation] = 8 , s [sample standard deviation] = s

n [no of items] = 8

H0 [Null] : σ = 8 ; H1 [Alternate - Right Tail] : σ > 8

χ2 = (n - 1) . s^2 / σ^2

= 49 x (10.5)^2 / 82 = 5402.25 / 64

χ2 = 84.410

df [degree of freedom] = n -1 = 50 - 1 = 49

P value (χ^2 49 > 84.410) = 0.00125

p = 0.0013

p < α ie 0.05

So, H0 is rejected

Hence we state that standard deviation is > 8 miles per hpur