# Standard Deviation and Deviation X. Suppose

Pages: 6 (1259 words) Published: April 8, 2013
A survey is conducted in Chicago (population 2,800,000) using random-digit-dialing equipment which place calls at random to residential phones, both mobile and landline. The purpose of the survey is to determine the percentage of adults who would favor a half-cent increase in the sales tax to help fund public transportation. Four hundred adults are interviewed and 36% of them favor the proposal. Answer the next two questions.

1. The sample size for this sample survey appears to be
a) 400
b) 2,800,000
c) 144
d) 1,008,000

2. The 36% is a
a) Parameter
b) Margin of error
c) Chance of 144 people agreeing to the statement
d) Statistic

3. Event A occurs with probability 0.05. Event B occurs with probability 0.75. If A and B are disjoint, which statement is true? a) P(A and B) = 0
b) P(A or B) = 0.80
c) P(A and B) = 0.0375
d) Both (a) and (b) are true.

4. Event A occurs with probability 0.05. Event B occurs with probability 0.75. If A and B are independent, which statement is true. e) P(A and B) = 0
a) P(A or B) = 0.80
b) P(A and B) = 0.0375
c) Both (a) and (b) are true.

A marketing research firm wishes to determine if the adult men in Laramie, Wyoming would be interested in a new upscale men's clothing store. From a list of all residential addresses in Laramie, the firm selects a simple random sample of 100 and mails a brief questionnaire to each. Use this information to answer the next three questions.

5. The population of interest is
a) all adult men in Laramie, Wyoming.
b) all residential addresses in Laramie, Wyoming.
c) the members of the marketing firm that actually conducted the survey. d) the 100 addresses to which the survey was mailed.

6. The sample in this survey is
a) all adult men in Laramie, Wyoming.
b) all residential addresses in Laramie, Wyoming.
c) the members of the marketing firm that actually conducted the survey. d) the 100 addresses to which the survey was mailed.

7. The chance that all 100 homes in a particular neighborhood in Laramie end up being the sample of residential addresses selected is a) the same as for any other set of 100 residential addresses. b) exactly 0. Simple random samples will spread out the addresses selected. c) reasonably large due to the “cluster” effect.

d) 100 divided by the size of the population of Laramie.

Costs for standard veterinary services at a local animal hospital follow a Normal distribution with a mean of \$80 and a standard deviation of \$20. Answer the next three questions.

8. Give the sample space for the costs of standard veterinary services. a) {X ≥ 0}
b) { 0 ≤ X ≤ 80}
c) {0 ≤ X ≤ 160}
d) None of these.

9. What is the probability that one bill for veterinary services costs less than \$95? a) 0.75
a) 0.7734
b) 0.2266
c) 0.15

10. What is the probability that one bill for veterinary services costs between \$75 and \$105? a) 1
a) 0.25
b) 0.4013
c) 0.4931

11. In an instant lottery, your chances of winning are 0.2. If you play the lottery five times and outcomes are independent, what is the probability that you win at least once? a. 0.2
a) 0.08192
b) 0.32768
c) 0.67232

A commuter must pass through 4 traffic lights on her way to work, and will have to stop at each one that is red. Let the random variable be X = number of red lights. The following table is the probability distribution for X. Answer the next four questions. |X |P(X = x) |

|0 |0.05 |
|1 |0.25 |
|2 |0.15 |
|3 |0.40 |
|4 |0.15 |

12. Give the sample space S for the number of red lights that the commuter stops at. a) {1, 2, 3, 4}
b) {0, 1, 2, 3, 4}
c) {0.05, 0.25, 0.15, 0.40, 0.15}
d) {0, 3, 2, 3, 3, 3, 2, 4, 3, 3, 3, 2, 0, 3 }

13. What is the probability that the commuter...

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