Suppose p and 112 are true mean stopping distances at 50 mph

Suppose p and 112 are true mean stopping distances at 50 mph for cars of a certain type equipped with two different types of braking systems. The data follows: m = 8, x = 114.9, s1 = 5.06, n = 8, y = 129.7, and s2 = 5.33. Calculate a 95% CI for the difference between true average stopping distances for cars equipped with system 1 and cars equipped with system 2. (Round your answers to two decimal places.) ( , ) Does the interval suggest that precise information about the value of this difference is available? Because the interval is so wide, it appears that precise information is available. Because the interval is so wide, It appears that precise information ?s not available. Because the interval is so narrow, it appears that precise information is not available. Because the interval is so narrow, it appears that precise information is available.hat precise information is available.

Solution

z for 95% CI= 1.96
declare p larger than alpha=0.05 not significant.

mean1 eq: 114.9 (variance= 25.604) (se= 1.789)
mean2 eq: 129.7 (variance= 28.409) (se= 1.8844)

Probability that var1<var2
p=0.55278 (left: 0.4472; double: 0.8944)

Difference between means:
M1-M2=114.9-129.7=-14.8
sd=9.7091; se=2.5984
95% CI of difference:
-19.8927 <-14.8< -9.7073

p value =0

Reject the hypothesis

H0 is rejected.

Because the interval is so narrow the precise information not available