A lunch bar has an average sales amount of $8.53. The manager initiates staff training to try to get them to sell more extras (chips, drinks etc), and after this training, a sample of 53 customers had the following sample statistics:
x̄ = 9.14 and s = 2.16
Assume our question of interest is: "is there significant evidence that the mean amount spent by customers has increased?" Calculate the observed value of the test statistic (correct to 2dp).
A hypothesis test for a population mean is to be conducted based on a sample of size 25. What is the correct distribution for the test statistic (assume that the population variance is not known)?
a. N(0,1), since the sample size is small we need to assume a normal distribution.
b. N(0,1), as the sample mean is normal by Central Limit Theorem.
c. t25, since the sample size is small, and we need to assume that the population is normally distributed.
d. t24, since the sample size is small, and we need to assume that the population is normally distributed.
A hypothesis test for a population mean has p-value 0.01. What is the decision at the 2.5% level of significance?
a. Since p-value < 0.025, we reject the null hypothesis.
b. Since p-value < 0.025, we accept the alternative hypothesis.
c. Since p-value < 0.025, we reject the alternative hypothesis.
d. Since p-value > 0.025, we fail to reject the null hypothesis.