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# Practice Quiz - Statistics

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1. The cumulative probability distribution of a random variable X gives the probability that X is _______ to x_0, some specified value of X.
a. Greater than or equal c. Less than or equal
b. Equal d. None of the above

2. By using the binomial table, if the sample size is 4 and p equals to 0.20, what is the value for P(X≥2)?
a. 0.4695 c. 0.1820
b. 0.8192 d. 0.1808

3. Thirty trials are conducted in the Bernoulli process in which the probability of success in a given trial is 0.6. What is the value of σ_x?
a. 7.20 c. 5.46
b. 2.68 d. 2.19

4. What is the area under the normal curve that lies between Z = -2.50 to Z = 1.05.
a. 0.8442 c. 0.8938
b. 0.8900 d. 0.8469

5. What is Z_0 score for P(Z≥Z_0) = 0.0708?
a. 1.47 c. 1.80
b. 1.35 d. 1.41

6. What is the value for 95% confidence interval for μ if s = 7.3, x = 84.2, and n = 40.
a. 81.937≤μ≤86.463 c. 74.093≤μ≤79.337
b. 68.767≤μ≤72.033 d. 61.364≤μ≤66.846

7. A random sample of 81 items is taken producing a sample mean of 47 and a sample standard deviation of 5.89. What is the value for 90% confidence interval to estimate the population mean?
a. 52.3844≤μ≤61.8966 c. 62.3541≤μ≤68.1359
b. 45.9267≤μ≤48.0733 d. 47.8252≤μ≤53.5478

8. What is the Z score in a normal distribution with μ = 75, σ^2 = 100 that are between 60 and 80?
a. 0.1585 c. 0.6247
b. 0.2139 d. 0.1598

9. In a standard normal distribution, what is the area which lies between Z = -1.82 and Z = 2.56?
a. 0.4948 c. 0.8305
b. 0.2123 d. 0.9604

10. The random variable x has a normal distribution with μ = 40 and σ^2 = 36. What is the value of x if P(X≥X_0) = 0.40?
a. 47.86 c. 49.85
b. 41.50 d. 45.73

True/False
_____11. A normal distribution is a distribution of discrete data that produces a bell-shaped.
_____12. For the normal distribution, the observations closer to the middle will occur with increasing frequency.
_____13. There are 2 types of random variable which are discrete random variable and continuous random sample.
_____14. The variance is the expected value of the squared difference between the random variable and its mean.
_____15. For the normal distribution, one-half of the observation are above the mean and one - half are below it.
_____16. Most of the normal distribution can be converted into a single distribution: the Z distribution.
_____17. The H_o cannot be written without having an equal sign.
_____18. The binomial probability table gives probability for value of p greater than 0.5.
_____19. The mean of the discrete probability distribution for a discrete random variable is called its expected value.
_____20. A standard Z table score can be used to find probability for any normal curve problems that have been converted to Z scores.