Statistics and Probability Answers

The lifetime of an alkaline battery (measured in hours) is exponentially distributed with μ = 0.05. Find the probability a battery will last between 10 and 15 hours.

The number of calls received by ABC Company follows Poisson distribution with an average of 6 calls per hour.

(a) Find the probability that there will be exactly 3 calls received in an hour. Answer: 

(b) Find the probability that there will be at least 2 calls received in an hour. Answer: 

(c) Find the probability that there will be exactly 2 calls received in 10 minutes. Answer: 

The relationship between mean and variance of X square with n degree of freedom

1. The recent Statistics test scores of Grade 1 pupils of Baesa Elementary School is normally distributed with a mean of 41 and a standard deviation of 6. If a random sample of 60 pupils is selected and their scores are recorded, (A) find the probability that their average score is greater than 40 but less than 42, and, (B) determine the number of sample means falling below 40. (25points). Note the standard error formula is n

For the following items, sketch the graphical representation and identify whether the z-values

fall within the rejection region or in the acceptance region.

a. Z = 2, 95% confidence, two-tailed

b. Z = -2.68, 95% confidence, two-tailed

c. Z = 1.8, 95% confidence, one-tailed

d. Z = 1.33, 99% confidence, one-tailed

e. Z = -4.0, 99% confidence, two-tailed

The performance by a defined group on a particular test is called

a. quartile

b. median

c. norm

d. tracking score

In order to rank group members in relationship to the number of other members of groups of arbitrary size, you would use the

Let X_1,X_2,......,X_n be independently and identically distributed b(1, p) random 

variables. Obtain a confidence internal for p using Chebychev’s inequality.

Let A and B be disjoint events and assume that Pr(A) = Pr(B) and Pr(AUB) = 0.8. Then Pr(A) =

Select one:

a. 0.4

b. 0.1

c. 0.2

d. 0.3