Twenty dogs and 20 cats were subjects in an experiment to test the effectiveness of a new flea control chemical.
Ten of the dogs were randomly assigned to an experimental group that wore a collar containing the chemical, while the others wore a similar collar without the chemical. The same was done with the cats. After 30 days veterinarians were asked to inspect the animals for fleas and evidence of flea bites. This experiment is
A) randomized block, blocked by species
B) completely randomized with one factor: the type of collar
C) completely randomized with two factors
D) completely randomized with one factor: the species of animal
E) randomized block, blocked by type of collar
Q. 2An appliance store sells both new and used appliances. Fifty percent of the stock is used. Fifty-two percent is used or defective. If 9 of the store's stock is defective, what percentage is both used and defective?
A) 7 B) 11 C) 93 D) 0.07
Q. 3Which of the following is a possible null hypothesis for a two-tailed hypothesis test?
A) x = 30 B) 30 C) 30 D) = 30
Q. 4The method of analysis of variance is not applicable for data in which sample sizes are not all equal.
Indicate whether the statement is true or false
Q. 5To check the effect of cold temperatures on the battery's ability to start a car researchers purchased a battery from Sears and one from NAPA.
They disabled a car so it would not start, put the car in a warm garage, and installed the Sears battery. They tried to start the car repeatedly, keeping track of the total time that elapsed before the battery could no longer turn the engine over. Then they moved the car outdoors where the temperature was below zero. After the car had chilled there for several hours the researchers installed the NAPA battery and repeated the test. Is this a good experimental design?
A) No, because they should have tested other brands of batteries, too.
B) Yes
C) No, because temperature is confounded by brand.
D) No, because the car and the batteries were not chosen at random.
E) No, because they should have tested more temperatures.
Q. 6If a distribution is known to be binomial, the most convenient formula that can be used to calculate the mean is
= xp(x) .
Indicate whether the statement is true or false
Q. 7In a recent survey, 82 of the community favored building more parks in their neighborhood. You randomly select 19 citizens and ask each if he or she thinks the community needs more parks.
Decide whether you can use the normal distribution to approximate the binomial distribution. If so, find the mean and standard deviation. If not, explain why.
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