Question

A study was conducted to determine success rates of students enrolled in the Statistics courses offered at South Plains College for the fall semester of 2015. A random sample of 14 students was taken, and we recorded each

student’s age, final average, gender, # hours worked per week, race, and the attendance record (# of classes not attended this semester). Use the results from the following table to answer all parts of #2

Age 21 18 18 19 43 24 25 50 18 17 20 21 26 20 Final Average Gender # Hrs worked/wk 25 35 40 25 40 Race Attendance 80 50 70 95 0 89 86 76 81 20 50 32 15 70 79 84 30 40 20

f. For the age variable, construct 3 graphs (histogram, stem and leaf plot, and box-plot). (6 pts)

g. For the age variable, describe the distribution (in terms of symmetry versus skewness) (1 pt)

h. For the age variable, compute the mean, median, and mode. (4 pts)

i. For the age variable, compute the range, variance, and standard deviation. (3 pts)

j. If one student is randomly selected from the sample, what is the probability that he/she will be over 25

years old? (2 pts)

k. For part j., did you use the classical, relative frequency (empirical), or subjective approach? (1 pt)

l. If three students are randomly selected, find the probability that at least one is a male. (3 pts)

m. Find the 95% confidence interval for the mean age of all Statistics students this semester. (3 pts)

n. If 4 students are randomly selected, what is the probability that all will be females? (3 pts)

o. We want to estimate the percentage of students next semester who earned a final average of 90 orabove. How many students must we survey next semester, if we want to be 95% confident that our

proportion estimate is within 3 percentage points? (2 pts)

Answer 1

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