A lunch bar has an average sales amount of $8.72.  The manager initiates staff training to try to get them to sell more extras (chips, drinks etc), and after this training, a sample of 57 customers had the following sample statistics:9.28 and s = 2.36Assume 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).

Example: The number of concurrent users for an ISP has historically averaged 5000. After a marketing campaign, the management would like to know if it has resulted in an increase in the number of concurrent users. To test this, data were collected by observing the number of concurrent users at 100 randomly selected moments of time. Suppose that the average and the standard deviation of the sample data are 5200 and 800, respectively. What is the null and alternative hypothesis if the study is to find for any evidence that the mean number of concurrent users has increased?

What is the value of the test statistic?

In 2013, the average Girl Scout in New York City sold 96 boxes of cookies. The leader of Troop 5078 in New York City wants to know if the scouts in her troop sold more cookies than the average in New York City. She randomly samples 50 girls in Troop 5078 and records the number of boxes of cookies sold for each girl in the sample.The troop leader finds that her Girl Scouts each sold an average of 101.1 boxes of cookies with a standard deviation of 29.3. She analyzed her data using a t-test and obtained a p-value of 0.11.What conclusion can she draw from her data? The sample value of 101.1 is significantly larger than 96. In other words, the data provide enough evidence to conclude that the mean number of boxes of cookies sold by Girl Scouts in Troop 5078 was higher than 96. Even though 101.1 is larger than 96, it is not significantly larger than 96. In other words, the data do not provide enough evidence to conclude that the mean number of boxes of cookies sold by Girl Scouts in Troop 5078 was higher than 96. Nothing. The conditions for use of a t-test were not met. She cannot trust that the p-value is accurate for this reason.

A researcher claims that the amounts of acetaminophen in a certain brand of cold tablets have a mean different from the 600 mg claimed by the manufacturer. Test this claim at the p < .05 level of significance. The mean acetaminophen content for a random sample of n = 41 tablets is 603.3 mg. Assume that the population standard deviation is 4.9 mg.Question 12Answera.Since the test statistic is greater than the critical z, there is sufficient evidence to reject thenull hypothesis and to support the claim that the mean content of acetaminophen is not600 mg.b.Since the test statistic is greater than the critical z, there is insufficient evidence to rejectthe null hypothesis and to support the claim that the mean content of acetaminophen isnot 600 mgc.Since the test statistic is greater than the critical z, there is sufficient evidence to acceptthe null hypothesis and to support the claim that the mean content of acetaminophen is600 mg.d.Since the test statistic is less than the critical z, there is sufficient evidence to reject thenull hypothesis and to support the claim that the mean content of acetaminophen is not600 mg.

A local fast food company sells a 16-oz soft drink. To determine if the soft drinks served contain less than the advertised 16 oz, a random sample of 20 drinks is chosen and the amount of drink in each cup is measured (without ice). The mean amount of soft drink was found to be 15.5 oz with a standard deviation of 0.4 oz. Based on the sample results we cannot claim that the soft drink contains less than 16 oz. Which form of statistical inference does this conclusion represent? Hypothesis testing Interval estimation Point estimation