Question

10. A manufacturer of automobile brake pads has developed a new type of pad designed to stop a car traveling at 60 mph faster than the old pads. The stopping distance for the old pads is approx. normal with μ = 100 feet & σ = 10 feet. A SRS of 35 cars is tested and x = 97 feet. Does this study provide evidence at the 5% significance level that the new brake pads are better?

Answer 1

10)

Solution :

This is the two tailed test .

The null and alternative hypothesis is ,

H₀ :   = 100

H_a : 100

Test statistic = z

= ( - ) / / n

= (97 - 100) / 10 / 35

= -1.775

Test statistic = -1.775

P(z < -1.775) = 0.0379

P-value = 2 * 0.0379 = 0.0758

= 0.05

P-value >

Fail to reject the null hypothesis .There is not sufficient evidence t the 5% significance level that the new brake pads are better