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 May 7th, 2019, 02:19 PM #1 Newbie   Joined: May 2019 From: Toronto Posts: 1 Thanks: 0 Ap statistics questions Hello, I am an English student taking my first statistics course Gonna be posting here a lot, because math is not my strong suit!!! These are some very basic statistic questions that I am struggling to answer at the moment. Any help will be greatly appreciated. Question 1: Water quality ratings (A, B, C, D, F) which reflect the risk of getting sick from swimming at any particular one of 36 Southern California beaches, are given in the following list: A A A F A A A B A C C A A F B A C A D F A D A A D A A D A A A A C F B A (a) (4 marks). Summarize the given ratings by constructing a relative frequency distribution and a bar chart. (b) (2 marks). Assuming that an A means little risk of getting sick, does it appear that the majority of beaches in Southern California are safe? On what information do you base your answer? (c) Would it be appropriate to construct a dotplot for these data? Why or why not? Question 2) Suppose that the distribution of marks on an exam is closely described by a normal curve with a mean of 65. The 84th percentile of this distribution is 75. (a) What is the 16th percentile? (b) What is the approximate value of the standard deviation of exam marks? (c) What z score is associated with an exam mark of 50? (d) What percentile corresponds to an exam mark of 85? (e) Do you think there were many marks below 35? Explain. Question 3) (a) A sample consisting of four pieces of luggage was selected from among those checked at an airline counter, yielding the following data on x = weight (in pounds): x1 = 33.5, x2 = 27.3, x3 = 36.7, x4 = 30.5 2 Suppose that one more piece is selected; denote its weight by x5. Find a value of x5, other than 32, such that ¯x = sample median. (b) An instructor has graded 19 exam papers submitted by students in a class of 20 students, and the mean mark so far is 70. (The maximum possible mark is 100.) How high would the mark on the last paper have to be to raise the class mean by 1 mark? By 2 marks? Question 5: The following data are the ages (in years) at diagnosis for 20 patients under treatment for meningitis: 18 18 25 19 23 20 69 18 21 18 20 18 18 20 18 19 28 17 18 18 (a) Calculate and interpret the values of the sample mean, variance, and standard deviation. (b) Compute the 10% trimmed mean and the sample median. Why might you recommend either one of these two statistics as measures of centre rather than the sample mean? (c) Compute the upper quartile, the lower quartile, and the interquartile range. This will be the best Bday present ever!!!!!!!!! Last edited by skipjack; July 10th, 2019 at 06:26 PM.
 July 10th, 2019, 06:29 PM #2 Global Moderator   Joined: Dec 2006 Posts: 20,973 Thanks: 2224 Do you still need help with these?

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