Text: Barbara Illowsky Page 271, Problem 88
A school newspaper reporter decides to randomly survey 12 students to see if they will attend Tet (Vietnamese New Year) festivities this year.
Based on past years, she knows that 18% of students attend Tet festivities. We are interested in estimating the number of the 12 students surveyed who will attend the festivities.
X is the number of students willing to attend Tet (Vietnamese New Year) festivities this year.
X can take on values of 0 through 12
Use the Binomial Distribution to answer the following questions:
a. How many of the 12 students do we expect (on average) to attend the festivities?
Enter answer rounded to 2 decimal places.
b. Find the probability that at most four students will attend.
Enter answer as decimal number rounded to 2 places and with a 0 to the left of the decimal point.
Do not enter answer as a percent.
c. Find the probability that more than two students will attend.
Enter answer as decimal number rounded to 2 decimal places with a 0 to the left of the decimal point.
Do not enter answer as a percent.
Question 4
Textbook Illowsky Page 406 Problem 96
Xbar is notation for average .
Excel =NORM.DIST()
A typical adult has an average IQ score of 105 with a standard deviation of 20.
If twenty (25) randomly selected adults are given an IQ test:
a What is the probability that the sample mean (xbar) scores will be equal to or less than 100 points?
Find the probability that P( Xbar =< 100 )
Enter answer rounded to 2 decimal places.
Include a 0 to the left of the decimal point if your answer is less than 1.
Do not enter answer as a percent.
b What is the probability that the sample mean scores will be between 100 and 115 points?
Find the probability that P(100 <= X =< 115)
Enter answer rounded to 3 decimal places with a 0 to the left of the decimal point.
Do not enter answer as a percent.
Question 5
Textbook Illowsky Page 400 Problem 62
http://stattrek.com/online-calculator/normal.aspx
Excel
=NORM.DIST()
=NORM.INV()
Suppose that the distance of fly balls hit to the outfield (in baseball) is normally distributed with a mean of 250 feet and a standard deviation of 50 feet. We randomly sample 49 fly balls.
X ¯ is notation for the average value of the x's.
If X ¯ = average distance in feet for 49 fly balls, then X ¯ ~ _______(_______,_______)
For the following three blanks fill in the correct answers.
For blank 1 Select the appropriate distribution by entering the corresponding letter.
a Normal Population Distribution (parent)
b Normal Sampling Distribution
For blank 2 What is the numerical value of the mean( mu) ?Enter answer with 0 decimal precision (Integer).
For blank 3 What is the Standard Deviation of the Sampling Distribution? (The standard error of the mean). Enter answer with 2 decimal place precision.
What is the probability that the 49 balls traveled an average distance of less than 240 feet?
The P(X ¯ < 240) =
Enter answer to 3 decimal place precision.
Do not enter answer as a percent. Include a 0 to the left of the decimal point.
Find the 80th percentile of the Sampling Distribution of Averages for the average of the 49 fly balls.
Find the X ¯ value such that P(X < X ¯) = .80
Enter answer to 1 decimal place precision.