Question

1.

The confidence intervals for the population proportion are generally based on ________.

		the t distribution when the population standard deviation is not known
		the z distribution
		the t distribution
		the z distribution when the sample size is very small

2.

The difference between the two sample means   1 –   2 is an interval estimator of the difference between two population means μ 1 –  μ 2.

True

False

3.

Excel does not have a special function that allows to calculate  t values.

True

False

4.

The sampling distribution of   is based on a normal distribution on samples of any size.

True

False

5.

A medical devices company wants to know the number of hours its MRI machines are used per day. A previous study found a standard deviation of four hours. How many MRI machines must the company find data for in order to have a margin of error of at most 0.5 hour when calculating a 98% confidence interval?

		425
		347
		346.26
		424.69

Answer 1

Solution-:

(1) The confidence intervals for the population proportion are generally based on the Z- distribution.

(2) The difference between the two sample means1 - sample mean2 is an interval estimator of the difference
  between two population means : True

Because, the point estimate for the difference in population means is the difference in sample means is

(3) True, MS-excel have a special command that follows to calculate t-value:

function used: "TDIST(x,degree of freedom,tails)"

(4) The sampling distribution of is based on a normal distribution on samples of any size false.

Becasuse, If x1, x2, .....xn is random sample from then probability distribution of statistic T( x1, x2, .....xn) is called as sampling distribution.