Biology Forums - Study Force

The number of degrees of freedom used in the two-sample t test for independent samples are the same as the degrees of freedom used in the construction of a confidence interval for 1 - 2.
  1.True
  2.False

Q. 2

The number of degrees of freedom of the two-sample t test are the same as the degrees of freedom for the paired t test statistic.
  1.True
  2.False

Q. 3

When testing a hypothesis concerning the difference of two independent population means, if the variance of the difference is estimated using the sample variances, the resulting test statistic has a Normal distribution.
  1.True
  2.False

Q. 4

The large sample z test for 1 - 2 can be used as long as at least one of the two sample sizes, n1 and n2, is greater than or equal to 30.
  1.True
  2.False

Q. 5

A survey was conducted on campus to learn about the average time that students spend in volunteer service per week. A random sample of 20 female college students and an independent random sample of 18 male college students were obtained and the number of volunteer hours per week was recorded. A 90 confidence interval for the difference in the population mean number of volunteer hours per week, F  M is given by (0.4, 2.6).
  Based on this interval, does there appear to be a difference in the number of volunteer hours per week between females and males, on average?
  1.Yes, because 0 is not in the interval.
  2.No, because 0 is not in the interval.

Q. 6

A survey was conducted on campus to learn about the average time that students spend in volunteer service per week. A random sample of 20 female college students and an independent random sample of 18 male college students were obtained and the number of volunteer hours per week was recorded. A 90 confidence interval for the difference in the population mean number of volunteer hours per week, F  M is given by (0.4, 2.6).
  Which value correctly completes the sentence: One can say with 90 confidence that the margin of (sampling) error is  _____ hours per week.
  1.1.5
  2.2.2
  3.1.1

Q. 7

Revenues reported last week from 25 randomly selected stores owned by an international clothing company averaged 59,540 with a standard deviation of 9,025. Suppose a second random sample of size 25 was taken and a 90 confidence interval was created and compared to the 95 confidence interval for the mean revenues of all the stores. Select the only correct statement below.
  1.The 90 confidence interval will be narrower than the 95 confidence interval since the multiplier value is smaller.
  2.The 90 confidence interval will be narrower than the 95 confidence interval since it is less accurate.
  3.The 90 confidence interval will be wider than the 95 confidence interval since we trade off a lower confidence level to a wider interval.
  4.We have insufficient information to determine exactly which interval will be wider.

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