820 brushes decreased by 25%
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Answer:
Step-by-step explanation:
Given that :
population mean μ = 120
sample size n = 37
sample mean x = 111
standard deviation = 21
The null hypothesis and the alternative hypothesis can be computed as:
The null hypothesis:
The alternative hypothesis:
Since this test is two-tailed, the value for the test statistics can be computed as:
z = -2.605
z = -2.61
Since this is a two-tailed test
P-value = 2(z < -2.61)
From the z table;
P-value = 2(0.0045)
P -value = 0.009
Decision rule: To reject the null hypothesis if the p-value is lesser than the level of significance
Conclusion: We reject the null hypothesis since the p-value is lesser than the level of significance. Thus, there is sufficient evidence to conclude that the average breaking distance differs from 120 feet.