Question

XIII. STAND ALONE PROBLEMS: USE THE INFORMATION IN EACH PROBLEM TO ANSWER PROBLEMS 41-44 41. What can we say about the percentage of data that lies within two standard deviations of the mean in large data set that shows a slight skew to its distribution? Round to the nearest tenth of a percent as necessary a) Approximately 75% b) At least 75% c) Approximately 95% d) At most 25% e) None of the above 42. A sample of 124 mice was divided into two groups, 84 receiving a standard dose of pathogenic bacteria followed by an antiserum and a control group of 40 not receiving the antiserum. After 3 weeks the numbers dead and alive in each group were counted. (Source UCD class pages). Test the appropriate hypothesis at the a = 0.01 to decide if there is an association between mortality (dead or alive) and treatment. The following is the summary of the data. Choose the most appropriate equation for answering this question. Dead Alive Total Antiserum 65 84 18 Total 87 124 a) x2 = 2 (observed-expected)? expected Control 19 37 22 40 b) FE MST MSE Z d) P(x) = nCxp* (1 - p)-* e) None of the above PAGE 1 OF 1 88 WORDS

Answer 1

41)since distribution is unknown, from Chebychev theorem

at least 75% values are within 2 standard deviation from mean

b) At least 75%

42)

since it is a chi square test of independence:

option a) is correct