Question

A new design for the braking system on a certain type of car has been proposed. For the current system, the true average braking distance at 40 mph under specified conditions is known to be 120 ft. It is proposed that the new design be implemented only if sample data strongly indicates a reduction in true average braking distance for the new design (a) Define the parameter of interest. O p-true proportion of cars whose braking distances reduced μ-true average braking distance for the new design u-true average braking distance for the old design Op true proportion of cars whose braking distances did not reduce State the relevant hypotheses. Ho: p 120 H 120 Ho: μ 120 Ha: μ # 120 H: 120 но, щ 120 Ha: μ < 120 H0: μ = 120 Ha: μ > 120 (b) Suppose braking distance for the new system is normally distributed with σ = 11, Let X denote the sample average braking distance for a random sample of 36 observations, which values of x are more contradictory to Ho than 117.2?

Answer 1

a)
Option B

H0: mu = 120
Ha: mu < 120

b)
xbar <= 117.2

test statistic,
z = (117.2 - 120)/(11/sqrt(36))
z = -1.5273

p-value = 0.0633

Option A