Question

(1 point) 5555 people are randomly selected and the accuracy of their wristwatches is checked, with positive errors representing watches that are ahead of the correct time and negative errors representing watches that are behind the correct time. The 5555 values have a mean of 119119sec and a population standard deviation of 155155sec. Use a 0.010.01 significance level to test the claim that the population of all watches has a mean of 00sec (use a two-sided alternative).

The test statistic is

The P-Value is

The final conclustion is

Answer 1

Given that, sample size (n) = 55

sample mean = 119 sec and

population standard deviation = 155 sec

The null and alternative hypotheses are,

H0 : μ = 0 sec

Ha : μ ≠ 0 sec

Test statistic is,

The test statistic is 5.6937

p-value = 2 * P(Z > 5.6937) = 2 * 0.0000 = 0.0000

The p-value is 0.0000

Since, p-value is less than 0.01 significance level, we reject the null hypothesis.

The final conclusion is :

The results are statistically significant. There is evidence that the mean is not equal to 0.