Complete question :
An FBI survey shows that about 30% (i.e., 0.3) of all property crimes go solved. Suppose that in New York City 15 such crimes are committed and they are each deemed independent of each other.
a. What is the probability that exactly 3 of these 15 crimes will be solved? b. What is the probability that at most 3 of these 15 crimes will be solved? c. What is the probability that more than 11 of these 15 crimes will be solved?
Answer:
0.17
0.29686
0.000092
Step-by-step explanation:
Given that :
Probability of success (p) = 0.3
Number of cases (n) = 15
1 - p = 1 - 0.3 = 0.7
Usung binomial distribution formula :
a. What is the probability that exactly 3 of these 15 crimes will be solved?
P(x = 3)
Recall:
P(x = x) = nCx * p^x * (1 - p)^(n-x)
P(x = 3) = 15C3 * 0.3^3 * 0.7^12
P(x = 3) = 455 *
P(x = 3) = 0.17
B.) What is the probability that at most 3 of these 15 crimes will be solved?
P( X ≤ 3) = P(x = 0) + p(x = 1) + p(x = 2) + p(x = 3)
To save computation time, we can using the binomial probability calculator :
P( X ≤ 3) : 0.00474 + 0.03052 + 0.09156 + 0.17004 = 0.29686
c. What is the probability that more than 11 of these 15 crimes will be solved?
P( X > 11) = P(x = 12) + p(x = 13) + p(x = 14) + p(x = 15)
P( X > 11) = 0.000092
, which equals 
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