Answer:
Yes, we reject the auto maker's claim.
Step-by-step explanation:
H0 : μ ≥ 20
H1 : μ < 20
Sample mean, xbar = 18 ;
Sample size, n = 36
Standard deviation, s = 5
At α = 0.01
The test statistic :
(xbar - μ) ÷ s /sqrt(n)
(18 - 20) ÷ 5/sqrt(36)
-2 /0.8333333
= - 2.4
Pvalue from test statistic : Pvalue = 0.00819
Pvalue < α
0.00819 < 0.01
Hence, we reject the Null
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0.2539
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