Download ProbStat Practice Quiz 6.3-6.4.tst

Prob/Stat PRACTICE Quiz 6.3-6.4
Name___________________________________
1) If the standard deviation of a normally distributed population is 24.0 and we
take a sample of size 4, then the standard error of the mean is
1)
2) In order to have the standard error of the mean be 14, one would need to take
samples from a normally distributed population with a standard
deviation of 56.
2)
3) A sample of size 60 will be drawn from a population with mean 14 and standard
deviation 7. Find the probability that x will be less than 15.
3)
4) A sample of size 58 will be drawn from a population with mean 18 and standard
deviation 12. Find the probability that x will be greater than 20.
4)
5) A sample of size 95 will be drawn from a population with mean 22 and standard
deviation 13. Find the probability that x will be between 19 and 23.
5)
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6) The average age of doctors in a certain hospital is 47.0 years old. Suppose the
distribution of ages is normal and has a standard deviation of 10.0 years. If 25
doctors are chosen at random for a committee, find the probability that the
average age of those doctors is less than 48.4 years.
6)
7) A certain car model has a mean gas mileage of 29 miles per gallon (mpg) with a
standard deviation 4 mpg. A pizza delivery company buys 49 of these cars.
What is the probability that the average mileage of the fleet is greater than
29.2 mpg?
7)
8) A certain car model has a mean gas mileage of 31 miles per gallon (mpg) with a
standard deviation 3 mpg. A pizza delivery company buys 59 of these cars.
What is the probability that the average mileage of the fleet is between 30.8 and
31.5 mpg?
8)
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9) Use the normal approximation to the binomial to find that probability for the
specific value of X.
n = 40, p = 0.8, X = 24
9)
10) Use the normal approximation to find the indicated probability. The sample size
is n, the population proportion of successes is p, and X is the number of
successes in the sample.
n = 86, p = 0.57: P(X ≥ 40)
10)
11) Use the normal approximation to find the indicated probability. The sample size
is n, the population proportion of successes is p, and X is the number of
successes in the sample.
n = 99, p = 0.5: P(X > 54)
11)
12) Use the normal approximation to find the indicated probability. The sample size
is n, the population proportion of successes is p, and X is the number of
successes in the sample.
n = 103, p = 0.47: P(X ≤ 46)
12)
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13) Use the normal approximation to find the indicated probability. The sample size
is n, the population proportion of successes is p, and X is the number of
successes in the sample.
n = 79, p = 0.6: P(X < 39)
13)
14) Use the normal approximation to find the indicated probability. The sample size
is n, the population proportion of successes is p, and X is the number of
successes in the sample.
n = 105, p = 0.43: P(38 < X < 49)
14)
15) Use the normal approximation to find the indicated probability. The sample size
is n, the population proportion of successes is p, and X is the number of
successes in the sample.
n = 89, p = 0.44: P(35 ≤ X ≤ 48)
15)
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Answer Key
Testname: PROBSTAT PRACTICE QUIZ 6.3-6.4
1) 12.0
2) 16
3) 0.8665
4) 0.1020
5) 0.7611
6) 75.8%
7) 0.3632
8) 0.5947
9) 1.34
10) 0.9808
11) 0.1562
12) 0.3520
13) 0.0207
14) 0.6503
15) 0.8180
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