A pharmaceutical company makes tranquilizers. It is assumed that the distribution for the length of time they last is approximately normal. Researchers in a hospital used the drug on a random sample of nine patients.
The effective period of the tranquilizer for each patient (in hours) was as follows: 2.7; 2.8; 3.0; 2.3; 2.3; 2.23 2.83; 2.13; and 2.4.

a. Identify the following.

x ^– = ___
sx =___

n =___

n-1 = ___

b. Which distribution should you use for this problem? Explain your choice.
c. Construct a 95% confidence interval for the population mean length of
time. State the confidence interval and calculate the error bound.
 

 pharmaceutical company makes tranquilizers. It is assumed that the distribution for the length of time they last is approximately normal. Researchers in a hospital used the drug on a random sample of 9 patients. The effective period of the tranquilizer for each patient (in hours) was as follows: 2.7; 2.9; 3.1; 2.3; 2.3; 2.2; 2.8; 2.1; and 2.4.

NOTE: If you are using a Student’s t-distribution, you may assume that the underlying population is normally distributed. (In general, you must first prove that assumption, though.)

(i) Round your answer to two decimal places.

 (rounded to two decimal places)

(ii) Round your answer to two decimal places.

 (rounded to two decimal places)

(iii) Enter an exact number as an integer, fraction, or decimal.

(iv) Enter an exact number as an integer, fraction, or decimal.