homework

1.      Which of the following variables are best thought of as continuous, which discrete? Indicate your choice for each by checking the appropriate column.

Variable                                                                                                           discrete                      continuous

·        The number or tickets purchased

·        Lifetime in hours of a 100 wat lite bulb

·        The fuel effenceify in miles per gallon of a American car

·        The total attendance of at a public school on a school day

2.      The stem-and-leaf display below gives the fuel efficiencies (in miles per gallon) for a sample of new cars. Use the display to answer the following questions.

1 /2

2/66

3/12223589

4/0668

5/046

1/2 means a fuel efficiency of 12 miles per gallon.                            

What is the lowest fuel efficiency in the 40s

What is the highest fuel efficiency in the sample overall

How many cars in the sample have the fuel efficiency in the 10s?

3.      Multiple myeloma is a form of cancer. For decades, there was no known treatment. Rather recently, though, doctors surmised that the drug Thalidomide, which was given to pregnant women in the s but was subsequently found to cause birth defects, may extend the lives of those afflicted with multiple myeloma.

In an extensive clinical trial, patients diagnosed as having multiple myeloma were treated with Thalidomide, and the subsequent number of months that each survived was recorded. Suppose that the following histogram summarizes the data from the sample:

Based on the histogram, find the proportion of survival times in the sample that are at least months. Write your answer as a decimal, and do not round your answer.

5.      The monthly salaries (in thousands of dollars) of a sample of sales representatives are as follows:

               6,8,12,11,8

Find the standard deviation of this sample of monthly salaries. Round your answer to at least two decimal places.

8.            An experiment involves participants. From these, a group of participants is to be tested under a special condition. How many groups of participants can be chosen, assuming that the order in which the participants are chosen is irrelevant?

9.                                                                                      

                              Suppose that A and B are independent events such that P (A)= 70 and  .              P(B)=.60. Find and  P(A  B)= ___ and P(A  B)= ___