In: Math
A total of 150 crimes were reported by the sheriff last year. Of the 150 crimes, 39 were committed by criminals under 20 years of age, 36 were committed by criminals over 40 and 82 were violent crimes. There were 27 violent crimes under the age of 20 and 14 violent criminals over the age of 40.
Type of Crime | Under 20 | 20-40 | Over 40 | Total |
Violent | 27 | 41 | 14 | 82 |
Non Violent | 12 | 34 | 22 | 68 |
Total | 39 | 75 | 36 | 150 |
What is the probability that at least one out of four crimes is nonviolent? Please show work so I can understand how to get the answer
n : Number of crimes = 4
Probability that a crime is nonviolent = Number of crimes that are violent / Total number of crimes
From the given table,
Number of crimes that are violent = 82
Total number of crimes = 150
Probability that a crime is nonviolent = Number of crimes that are nonviolent / Total number of crimes = 68/150=34/75
Probability that a crime is violent = 1-Probability that a crime is nonviolent = 1-34/75 = 41/75
Probability that at least one out of four crimes is nonviolent = 1 - Probability that none of the 4 crimes are nonviolent
Probability that none of the 4 crimes are nonviolent = Probability that all 4 crimes are violent
Probability that all 4 crimes are violent
= Probability that 1st crime is violent x probability that 2nd crime is violent x probability that 3rd crime is violent x probability 4th crime is violent
= (41/75)*(41/75)*(41/75)*(41/75) = 0.089308002
Probability that none of the 4 crimes are nonviolent = Probability that all 4 crimes are violent = 0.089308002
Probability that at least one out of four crimes is nonviolent
= 1 - Probability that none of the 4 crimes are nonviolent = 1-0.089308002 = 0.910691998
Probability that at least one out of four crimes is nonviolent = 0.910691998