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 CLAST TEST # 3 :                   

7. The table below classifies a group of students according to the number of hours per week 
       spent using the computer. Find the probability that a randomly chosen student uses the computer
       for 19 or more hours per week.
Hours per week  Percent
less than 4 6%
4 - 8  28%
9 - 13 35%
14 - 18 19%
19 or more 12%

 
   
        A)  0.12                B)  0.19                    C) 0.28                       D) 0.06
 

  Solution:    
                When all outcomes are equally likely to occur, the probability of the occurrence of a given
                 outcome can be found by using the following formula:

                 probability =  number of favorable outcomes
                                      number of possible outcomes

                number of favorable outcomes: 12%  (a student use the computer for 19 or more hours per week)
                number of possible outcomes: 6% + 28% + 35% + 19% + 12% = 100%

               probability = 12%                              (12/100 = 0.12)
                                   100% 

               probability = 0.12

               

 Answer:  A)  0.12   

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