In company that makes sleeping drugs, it is assumed that the distribution for the length of period that last are approximately normal. An experiment was conducted on a random sample of nine patients. The effective period of the sedative for each patient (in hours) is given as 2.7; 2.8; 3.0; 2.4; 2.3; 2.2; 2.8; 2.1; and 2.4.

i)What is the mean

ii)What is the standard deviation

iii)What is the number of observations

iv)Which distribution should you use for this problem? Explain your choice.

v)Construct and state the confidence interval at 95%.

vi)Sketch the graphy.