Answer:
a.
b.
c. mean=2.8
d . standard deviation=1.2961
Step-by-step explanation:
We determine that the accident rates follow a binomial distribution. The rate of success p=0.4 and sample n=7:
#the probability of exactly three;
#At least(more than 2)
#At most 3;
b. Between 2 and 4:
Using the binomial expression, this probability is calculated as:
Hence,the probability of between 2 and four is 0.7451
c. From a above, we have the values of n=7 and p=0.4.
-We substitute this values in the formula below to calculate the mean:
-The mean of a binomial distribution is calculated as the product of the probability of success by the sample size, mean=np:
Hence, the standard deviation of the sample is 2.8
d. From a above, we have the values of n=7 and p=0.4
--We substitute this values in the formula below to calculate the standard deviation
-The standard deviation a binomial distribution is given as:
Hence, the standard deviation of the sample is 1.2961