500 câu trắc nghiệm Kinh tế lượng – 4B

11) Find the probability of selecting 9 or more girls.
● 0.212
○ 0.061
○ 0.001
○ 0.122

Answer the question.
12) Suppose that voting in municipal elections is being studied and that the accompanying tables describes the probability distribution for four randomly selected people, where x is the number that voted in the last election. Is it unusual to find four voters among four randomly selected people?

● Yes
○ No
Assume that a procedure yields a binomial distribution with a trial repeated n times. Use the binomial probability formula to find the probability of x successes given the probability p of success on a single trial.

13) n = 10, x = 2, p = 13

○ 0.2156
● 0.1951
○ 0.1929
○ 0.0028

Find the indicated probability.
14) An airline estimates that 91% of people booked on their flights actually show up. If the airline books 80 people on a flight for which the maximum number is 78, what is the probability that the number of people who show up will exceed the capacity of the plane?
● 0.0047
○ 0.0042
○ 0.0005
○ 0.0211

Find the standard deviation, \(\sigma \), for the binomial distribution which has the stated values of n and p. Round your answer to the nearest hundredth.
15) n = 1546; p = .57
○ \(\sigma \) = 23.59
● \(\sigma \) = 19.47
○ \(\sigma \) = 22.74
○ \(\sigma \) = 17.06

Use the given values of n and p to find the minimum usual value \(\mu – 2\sigma \) and the maximum usual value \(\mu + 2\sigma \).
16) n = 290, p = 1/4
○ Minimum: 87.25; maximum: 57.75
○ Minimum: 65.13; maximum: 79.87
○ Minimum: 62.07; maximum: 82.93
● Minimum: 57.75; maximum: 87.25

Solve the problem.
17) The probability of winning a certain lottery is 1/52,027. For people who play 724 times, find the mean number of wins.
○ 0.0719
○ 0.000019
○ 0.0014
● 0.0139

18) A company manufactures batteries in batches of 20 and there is a 3% rate of defects. Find the variance for the number of defects per batch.
● 0.582
○ 0.6
○ 0.553
○ 0.578

Determine if the outcome is unusual. Consider as unusual any result that differs from the mean by more
than 2 standard deviations. That is, unusual values are either less than \(\mu – 2\sigma \) or greater than \(\mu + 2\sigma \).
19) The Acme Candy Company claims that 60% of the jawbreakers it produces weigh more than .4 ounces. Suppose that 800 jawbreakers are selected at random from the production lines. Would it be unusual for this sample of 800 to contain 476 jawbreakers that weigh more than .4 ounces?
● No
○ Yes

Use the Poisson Distribution to find the indicated probability.
20) A computer salesman averages 1.5 sales per week. Use the Poisson distribution to find the probability that in a randomly selected week the number of computers sold is 0.
○ 0.2789
○ 0.2454
● 0.2231
○ 0.3347