Chapter 4: Q.20 (page 283)
Find the standard deviation.
Short Answer
Standard deviation is
Chapter 4: Q.20 (page 283)
Find the standard deviation.
Standard deviation is
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Get started for freeSuppose that the PDF for the number of years it takes to earn a Bachelor of Science (B.S.) degree is given in Table 4.31.
a. In words, define the random variable X.
b. What does it mean that the values zero, one, and two are not included for x in the PDF?
Use the following information to answer the next six exercises: On average, a clothing store gets customers per day.
What is the probability that the store will have fewer than customers in the first two hours?
A lacrosse team is selecting a captain. The names of all the seniors are put into a hat, and the first three that are drawn will be the captains. The names are not replaced once they are drawn (one person cannot be two captains). You want to see if the captains all play the same position. State whether this is binomial or not and state why.
An intramural basketball team is to be chosen randomly from 15 boys and 12 girls. The team has ten slots. You want to know the probability that eight of the players will be boys. What is the group of interest and the sample?
According to a Gallup poll, 60% of American adults prefer saving over spending. Let X = the number of American adults out of a random sample of 50 who prefer saving to spending.
a. What is the probability distribution for X?
b. Use your calculator to find the following probabilities:
i. the probability that 25 adults in the sample prefer saving over spending
ii. the probability that at most 20 adults prefer saving
iii. the probability that more than 30 adults prefer saving
c. Using the formulas, calculate the
(i) mean and
(ii) standard deviation of X.
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