Respuesta :
Answer:
Explained below.
Step-by-step explanation:
(a)
In this case we need to determine if the proportion of customer complaints has decreased by more than 10% under the new packaging design.
The hypothesis can be defined as follows:
H₀: The proportion of customer complaints has not decreased by more than 10% under the new packaging design, i.e. p₁ - p₂ ≤ 0.10.
Hₐ: The proportion of customer complaints has decreased by more than 10% under the new packaging design, i.e. p₁ - p₂ > 0.10.
(b)
The information provided is:
n₁ = 220
n₂ = 220
X₁ = 86
X₂ = 41
Compute the sample proportions and total proportions as follows:
[tex]\hat p_{1}=\frac{X_{1}}{n_{1}}=\frac{86}{220}=0.3909\\\\\hat p_{2}=\frac{X_{2}}{n_{2}}=\frac{41}{220}=0.1864\\\\\hat P=\frac{X_{1}+X_{2}}{n_{1}+n_{2}}=\frac{86+41}{220+220}=0.2886[/tex]
Compute the test statistic value as follows:
[tex]z=\frac{\hat p_{1}-\hat p_{2}}{\sqrt{\hat P(1-\hat P)[\frac{1}{n_{1}}+\frac{1}{n_{2}}]}}[/tex]
[tex]=\frac{0.3909-0.1864}{\sqrt{0.2886(1-0.2886)\times[\frac{1}{220}+\frac{1}{220}]}}\\\\=\frac{0.2045}{\sqrt{0.0018665}}\\\\=4.733524\\\\\approx 4.73[/tex]
The test statistic value is 4.73.
Compute the p-value as follows:
[tex]p-value=P(Z>4.73)[/tex]
[tex]=1-P(Z<4.73)\\=1-(\approx 1)\\=0[/tex]
The p-value of the test is 0.
(c)
The decision rule is:
The null hypothesis will be rejected if the p-value of the test is less than the significance level.
p-value = 0 < α = 0.01.
The null hypothesis will be rejected at 1%significance level.
Thus, there is enough evidence at 1% significance level to support the engineers' claim.
(d)
The decision rule is:
The null hypothesis will be rejected if the p-value of the test is less than the significance level.
p-value = 0 < α = 0.10.
The null hypothesis will be rejected at 10%significance level.
Thus, there is enough evidence at 10% significance level to support the engineers' claim.
