What are you drinking? Environmental Protection Agency standards require that the amount of lead in drinking water be less than 15 micrograms per liter. Eleven samples of water from a particular source have the following concentrations, in units of micrograms per liter. Assume the population standard deviation is G=3. If appropriate, perform a hypothesis test to determine whether you can conclude that the mean concentration of lead meets the EPA standards. Use the a=0.10 level of significance and the P-value method with the TI-84 Plus calculator. 11.7 14.3 11.7 14.9 15.9 12.8 8.7 12.1 17.7 9.6 15.6 Send data to Excel Part: 0 / 7 Part 1 of 7 (a) Explain why it is necessary to check that the population is approximately normal before performing a hypothesis test. It is necessary to check that the population is approximately normal because the sample size is small ≤ 30 Part: 1/7 5 Part 2 of 7 (b) Following is a dotplot of the data. Is it reasonable to assume that the population is approximately normal? It is reasonable to assume that the population is approximately normal. G

Given a mean, standard deviation, and a raw score, find the corresponding z-score. Assume the distribution is normal. mean 70, standard deviation 4, x = 80 What is the corresponding z-score? z=

Assume the samples are random and independent, the populations are nomally distributed, and the population variances are equal. The table available below shows the prices (in dollars) for a sample of automobile batteries. The prices are classified according to battery type. At a = 0.10, is there enough evidence conclude that at least one mean battery price is different from the others? Complete parts (a) through (e) below. E Click the icon to view the battery cost data. (a) Let u1. P2. H3 represent the mean prices for the group size 35, 65, and 24/24F respectively. Identify the claim and state Ho and H. H Cost of batteries by type The claim is the V hypothesis. Group size 35 Group size 65 Group size 24/24F 101 111 121 124 D 146 173 182 278 124 140 141 89 (b) Find the critical value, Fo, and identify the rejection region. 90 79 84 The rejection region is F Fo, where Fo = (Round to two decimal places as needed.) (c) Find the test statistic F. Print Done F= (Round to two decimal places as…

Consider a value to be significantly low if its z score less than or equal to −2 or consider a value to be significantly high if its z score is greater than or equal to 2.   A test is used to assess readiness for college. In a recent​ year, the mean test score was 21.4 and the standard deviation was 5.4. Identify the test scores that are significantly low or significantly high.   What test scores are significantly​ low? Select the correct answer below and fill in the answer​ box(es) to complete your choice.   A. Test scores that are between ____ and _____. (Round to one decimal place as needed. Use ascending​ order.)   B. Test scores that are less than _____. (Round to one decimal place as​ needed.)   C. Test scores that are greater than _____. ​(Round to one decimal place as​ needed.)