Answer
$\bar{x}$ = 1175 cubic feet, μ=1245 cubic feet,σ=250 cubic feet,$σ_\bar{s}$ =$ \frac{250}{$100}$, n = 100
By p value approach,
If α=0.025, .
p-value = P(Z>2.1) = 0.0026 > α
The p-value =0.0026 is larger than α , hence we failed to reject the null hypothesis and conclude that the mean consumption of water per household is not decreased due to the campaign by the city council.
α = 0.025, df = 100-1=99, critical value= 1.96
t=$ \frac{\bar{x}-μ }{σ_\bar{s}}$
= $ \frac{1175-1245 }{25}$
=-2.8
Rejection region = z< -1.96
Non rejection region = z > -1.96
The value t = -2.8 falls within the rejection region, hence we reject the null hypothesis and conclude that the mean consumption of water per household is decreased due to the campaign by the city council.
Work Step by Step
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