Ap Stat

find the probability of a randomly drawn marble being yellow, given that the marble is small? a) .39 b) .64 c) .14 d) .37 e) .23

.39

what's the probability that a randomly selected marble will be blue or white ? a) .34 b) .16 c) .50 d) .18 e) none

.50

if P(A) = .25 and P(B) = .34, what is P(A U B) if A and B are independent ? a) .085 b) .505 c) .590 d) .675 e) there is insufficient information to answer this question

.505

People with type O-negative blood are universal donors. That is, any patient can receive a transfusion of O-negative blood. Only 7.2% of the American population has O-negative blood. If 10 people appear at random to give blood, what is the probability that at least 1 of them is a universal donor? a) 0 b) .280 c) .526 d) .720 e) 1

.526

find the probability of a randomly drawn marble large, given that the marble is black. a) .35 b) .65 c) .22 d) .20 e) .80

.65

Suppose X and Y are independent random variables. The variance of X is equal to 16; and the variance of Y is equal to 9. Let Z = X-Y a) 2.65 b) 5.00 c) 7.00 d) 25.0

5.00

An auto analyst is conducting a satisfaction survey, sampling from a list of 10,000 new car buyers. The list includes 2,500 Ford buyers, 2,500 GM buyers, 2,500 Honda buyers, and 2,500 Toyota buyers. The analyst selects a sample of 40 car buyers, by randomly sampling 100 buyers of each brand. a) Yes, because each buyer in the sample was randomly sampled b) Yes, because each buyer in the sample had an equal chance of being sampled c) Yes, because car buyers of every brand were equally represented in the sample d) No, because every possible 400-buyer sample did not have an equal chance of being chosen e) No, because the population consisted of purchasers of four different brands of car

No, because every possible 400-buyer sample did not have an equal chance of being chosen

Two antidepressants are to be compared in the treatment of elderly patients in a nursing home. Each patient has his or her own room, some with spectacular views of the ocean. The experimental design is to create homogeneous blocks with respect to window view. How should randomization be used for a randomized block design? a) within each block, randomly pick half the patients to receive each antidepressant b) randomly pick half of all patients to receive each antidepressant, but then analyze the results the results separately by blocks c) randomly choose which blocks will receive which antidepressants d) randomly choose half the blocks to receive each antidepressants for a given time period; then for the same time period switch the medication in each block and compare the results e) for ethical reasons, allows patients to choose which medication they prefer taking, but them randomly assign patients to the blocks

Within each block, randomly pick half the patients to receive each antidepressant

measurements of water quality were taken from a river downstream from an abandoned chemical dumpsite. Concentrations of a certain chemical were obtained from 9 measurements taken at the surface of the water, 9 measurements taken at mid-depth of the water, and 9 measurements taken at the bottom of the water. What type of study was conducted, and what is the response variable of the study. a) an experiment was conducted, and the response variable is the concentration of the chemical b) an experiment was conducted, and the response variable is the depth of the water c) a census was conducted, and the response variable is the depth of the water d) an observational study was conducted, and the response variable is the concentration of the chemical e) an observational study was conducted, and the response variable is the depth of the water

an observational study was conducted, and the response variable is the concentration of the chemical

A bank wishes to survey its customers. The decision is made to randomly pick ten customers who just have checking accounts, ten customers who just have savings accounts, and ten customers who have both checking and savings accounts. This procedure is an example of which type of sampling? a) cluster b) convenience c) simple random d) stratified e) systematic

stratified

The back to back stemplot on the right shows the number of books read in a year by a random sample of college and high school student. Which of the following statements are true? 1) One college student read seven books 2) The college median is equal to the high school median 3) The mean is greater than the median in both groups

1 2 and 3

A critical difference between experiments and observational studies is a) an experiment often suggests a casual relationship, whereas an observational study only suggests as association b) observational studies make use of randomization, whereas experiments do not c) experiments are generally more cos and time effective than observational studies d) tests of significance can be used on data collected from experiments but not on data collected from studies e) experiments are free to choose subjects from an entire population, whereas an observational study only considers a random sample

an experiment often suggests a casual relationship, whereas an observational study only suggests as association

A materials engineer wishes to compare the durability of two different types of paving material. She has 40 different one-mile stretches of interstate highway that she's been authorized to repave for study. She decides to carry out a matched pairs experiment. Which of the following is the best way for her to carry out the randomization for this study? a) use a table of random digits to divide the 40 roadways into 20 pairs and then, for each pair, flip a coin to decide which pavement to use on which member of the pair b) subjectively divide the 40 roadways into 20 pairs (making the roadways within each pair as different as possible) and then, for each pair, flip a coin to decide which pavement to use on which member of the pair c) use a table of random digits to divide the 40 roadways into two groups of twenty, and then use the table of random digits a second time to decide which pavement to use on the which group d) let each of the 40 roadways act as its own pair, dividing each roadway into the first half-mile and the second half-mile. Flip a coin for each of the 40 roadways to decide which half-mile gets which pavement e) let each of the 40 roadways act as its own pair, dividing each roadway into the first half-mile and the second half-mile. Flip a coin once to decide which pavement is put on the first half-mile of all roadways.

let each of the 40 roadways act as its own pair, dividing each roadway into the first half-mile and the second half-mile. Flip a coin for each of the 40 roadways to decide which half-mile gets which pavement

A company wishes to survey what people think about a new product it plans to market. They decide to randomly sample from their costumer database as this includes phone numbers and addresses. This procedure is an example of which type of sampling? a) cluster b) convenience c) simple random d) stratified e) systematic

simple random

Which of the following statements is incorrect? a) voluntary response samples often under represent people with strong opinions b) convenience samples often lead to under coverage bias c) questionnaires with non-neutral working are likely to have response bias d) there is no way to fix the results if a biased sampling method was employed e) non-response bias should be avoided because those who do not respond might have different views from those who do respond

voluntary response samples often under represent people with strong opinions