Ap Stats Final Flashcards
(19 cards)
A random variable X has a mean of 120 and a standard deviation of 15. A random variable Y has a mean of 100 and a standard deviation of 9. If X and Y are independent, approximately what is the standard deviation of X - Y ?
17.5
From a random sample of 50 people, sitting pulse rates and standing pulse rates were measured for each person. A coin was flipped to determine whether the sitting or the standing pulse rate would be measured first. Let µsitting represent the mean sitting pulse rate in the population, µstanding represent the mean standing pulse rate in the population, and µd represent the mean of the differences between the sitting and standing (sitting - standing) pulse rates in the population. Which of the following represents an appropriate test and hypotheses to determine if there is a difference in mean pulse rates between sitting and standing in the population?
A matched-pairs t-test with H0 : μd = 0 and Ha : μd ≠ 0
The prices, in thousands of dollars, of 304 homes recently sold in a city are summarized in the histogram below.
The figure shows a histogram with the horizontal axis labeled Price, in thousands of dollars, and the left vertical axis labeled Number of Homes Sold. The horizontal axis has equally spaced tick marks labeled from 250 to 2,500 in increments of 250. The vertical axis has equally spaced tick marks labeled from zero to 140 in increments of 20. There are 9 bars on the histogram, centered between the tick marks, with the height given on the top of the bar as follows, from left to right: Bar between 250 and 500: height 38. Bar between 500 and 750: height 120. Bar between 750 and 1,000: height 82. Bar between 1,000 and 1,250: height 38. Bar between 1,250 and 1,500: height 10. Bar between 1,500 and 1,750: height 8. Bar between 1,750 and 2,000: height 5. Bar between 2,000 and 2,250: height 2. Bar between 2,250 and 2,500: height 1.
Based on the histogram, which of the following statements must be true?
The median price is not greater than 750,000
Skin cancer
190/86
Mice Kansas
IQR
College newspaper
13.75+-1.456
The random variable X is normally distributed with mean 5 and standard deviation 25. The random variable Y is defined by Y = 2 + 4X. What are the mean and the standard deviation of Y ?
22,100
Median appsrmbebt price is appsrtement
1300 1.3
The management team of a company with 10,000 employees is considering installing charging stations for electric cars in the company parking lots. In a random sample of 500 employees, 15 reported owning an electric car. Which of the following is a 99 percent confidence interval for the proportion of all employees at the company who own an electric car?
0.03+-2.576 (0.03)(0.97)/500
A test of the hypotheses H0 : µ = 0 versus Ha : µ > 0 was conducted using a sample of size 7. The test statistic was t = 1.935. Which of the following is closest to the p-value of the test?
0.0506
Cereal
2500
car manufacturer
0.283>0.05
Psychologist
A matched-pairs t-test for a mean difference
Commutes to work
0.0950
Florida and Coloradoe
There is not sufficient statistical evidence to conclude that the proportion of all overweight dogs in Florida is different from the proportion of all overweight dogs in Colorado because the p-value is greater than 0.05.
Professional
Soccer
The small p-value suggests that there is evidence of an association between category and opinion about the use of instant replay.
The table below shows historical data for the distribution of the number of customers, in half-hour time periods, who visit the electronics department of a retail store. For example, in 25 percent of the time periods for which data were collected, no customers were observed in the electronics department of the store.
A table is shown with two rows. The first row reads number of customers, 0, 1, 2, and 3 or more. The second row reads proportion of time periods, 0.25, 0.20, 0.30, and 0.25.
To investigate if the distribution has changed, the number of customers who visited the electronics department of the store was recorded for each of 50 randomly selected time periods. The results are shown in the table below.
A table is shown with two rows. The first row reads number of customers, 0, 1, 2, and 3 or more. The second row reads number of time periods, 4, 13, 14, and 19.
A chi-square goodness-of-fit test was conducted to determine whether the data provide convincing evidence that the distribution has changed. The test statistic was 10.13 with a p-value of 0.0175. Which of the following statements is true?
At the significance level α = 0.05, the data provide convincing evidence that the current distribution is different from the historical distribution.
Pain relieving
0.1802
A group of students wanted to investigate the claim that the average number of text messages sent yesterday by students in their school was greater than 100.
Because p > 0.05, at the 5% significance level, it cannot be concluded that the mean number of text messages sent yesterday by students in the school is greater than 100.
