The t-distribution allows the calculation of confidence intervals for means for small samples when the population variance is not known, regardless of the shape of the distribution in the population.
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Q. 2As a general rule, the normal distribution is used to approximate the sampling distribution of the sample proportion only if:
a. the sample size n is greater than 30
b. the sample size n is greater than 100
c. the population proportion p is close to 0.50
d. the underlying population is normal
e. np and n(1 - p) are both greater than or equal to 5
Q. 3The t-distribution allows the calculation of confidence intervals for means when the actual standard error is not known.
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Q. 4Given that X is a binomial random variable, the binomial probability P(X >= x) is approximated by the area under a normal curve to the right of:
a. x - 0.5
b. x + 0.5
c. x - 1
d. x + 1
e. x + 0.1
Q. 5In forming a 95 confidence interval for a population mean from a sample size of 20, the number of degrees of freedom from the t-distribution equals 18.
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Q. 6In general, the binomial probability P(X x) is approximated by the area under the normal curve to the right of x - .5.
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