Probability

Question

A car dealership surveys 10,000 of its customers who have a GPS system in their cars to find out how often they have used it within the past month. The results are as follows:

Number of Times Used                                       Customers with GPS
0                                                                         1382
1-5                                                                      2350
6-10                                                                    2010
11-15                                                                  1863
16-20                                                                  1925
21+                                                                      470

a) What is the probability that a randomly chosen customer will have used the GPS system more than 20 times?
b) What is the probability that a randomly chosen customer will have used the GPS system no more than 10 times?

Answer 1

a. Only 470 people of the surveyed drivers used GPS more than 20 times.

The probability is

P(sed the GPS system more than 20 times)=470/10,000

                                                              =0.047=4.7%.

 

b. Using GPS no more than 10 times is divided into three categories - no used, 1-5 and 6-10 uses. We add the number of people for each of these answers and divide by the total number of responses, 10000.

Number of people used GPS no more than 10 times = 1382+2350+2010=5742.

P(used the GPS system no more than 10 times) =5742/10000

                                                                      =0.5742=57.42%≈57%.