SOLUTION: A computer store has 10 copies of a word processing program, 12 copies of a spread sheet program, and 8 copies of a draw program. Three of the word processing, four of the spread

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Question 147638: A computer store has 10 copies of a word processing program, 12 copies of a spread sheet program, and 8 copies of a draw program. Three of the word processing, four of the spread sheet and two of the draw programs are infected with a computer virus. If a program is selected at random, the probability it is infected with a virus is:
Found 2 solutions by edjones, aswathytony:
Answer by edjones(8007) (Show Source):
You can put this solution on YOUR website!
If you choose at random you can choose from 10+12+8=30 programs of which 3+4+2=9 are infected.
9/30=3/10 probability you choose an infected one.
.
Ed

Answer by aswathytony(47) (Show Source):
You can put this solution on YOUR website!
Total number of computer pgms in store = 10 + 12 + 8 = 30 .

number of ways in which one pgm can be drawn out of 30 pgms = C(30,1) = 30.

Total number of virus affected pgms = 3+4+2 = 9

number of favorable cases = number of ways in which 1 pgm infected with
virus is selected from 9 infected pgms
= C(9,1) = 9
Required probability = 9/ 30 = 3/10