Intro. Vocabulary
A survey of 162 law firms in a country found that the average hourly billing rate for partners was $609. Identify the population and the sample.
Population: all law firms in the country
Sample: the 162 law firms that were surveyed
Calculate the sample mean and attach the correct symbol. Round to hundredths.
4 5 6 1 4 6 4 5 7
x-bar = 4.67
Draw one card from an ordinary deck. What is the probability of drawing a Jack or a Queen? Are these events mutually exclusive?
8/52 = 2/13 = 0.154
Yes, they're mutually exclusive.
Find the probability that a z-score is greater than 1.17.
0.1210
Beth is at the 30th percentile in weight among fifth graders. This means that Beth weighs less than _____% of fifth graders
70
A survey of 162 law firms in a country found that the average hourly billing rate for partners was $609. The $609 is an example of a _____________________.
sample statistic (or just statistic)
Calculate the median and mode.
4 5 6 1 4 6 4 5 7
median = 5
mode =4
Draw one card from an ordinary deck. What is the probability of drawing a Jack or a diamond? Are these events mutually exclusive?
16/52 =4/13 = .308
No, not mutually exclusive
Find the z-score that corresponds to the third quartile.
0.67
In a restaurant, a study is found that 42% of all patrons smoked. If the seating capacity of the restaurant is 80 people, find the mean, variance, and standard deviation of the number of smokers.
mean (mu) = 33.6
variance (sigma2)=19.488
standard deviation (sigma)=4.4
Annual income would be an example of ____________ data.
quantitative
Calculate the IQR.
4 5 6 7 4 6 4 5 7
2.5
Draw one card from an ordinary deck. What is the probability of drawing a Jack given it is a diamond?
1/13
IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. Find the probability that a randomly selected person has an IQ between 75 and 125.
0.9044 (calculator) or 0.9051 (z-scores)
IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. If 300 people are randomly selected, about how many people should have an IQ less than 110?
224 (calculator) or 225 (z-scores)
Randomly choosing 20 students from each of grades 9-12 would be an example of _____________ sampling.
stratified
Calculate the variance of the sample. Attach the correct symbol.
4 5 6 1 4 6 4 5 7
s2 = 3
Draw two cards from an ordinary deck, with replacement. What is the probability of drawing two Aces? (round to thousandths) Are these independent events?
0.006
Yes, independent
IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. Find the minimum IQ, to the nearest tenth, that will place a person in the top 10% of the population.
119.2
Calculate the sample mean and standard deviation of the following frequency distribution. Round to the nearest hundredth.
Class Frequency
230-235 6
236-241 8
242-247 5
248-253 3
254-259 2
x-bar = 241.25
s=7.50
Surveying all students in each of RCCC's statistics classes would be an example of ______________ sampling.
cluster
Values below _____ or above would be considered unusual. List any unusual values.
4 5 6 1 4 6 4 5 7
below 1.20 or above 8.13
1 is unusual
Draw two cards from an ordinary deck, without replacement. What is the probability of drawing two Aces? (round to thousandths) Are these independent events?
0.005
No, dependent
IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. If 50 people are randomly selected, find the probability that the sample mean is less than 95. Is this unusual?
0.0092 (calculator) or 0.0091 (z-scores)
Unusual
Annual salaries at a company have a mean of $50,000 with a standard deviation of $8000. Randomly select 80 people. Use Chebychev’s Theorem to determine at least how many of the people will have a salary between $34,000 and $66,000.
at least 60 people