Question

1. Lifetimes of a certain brand of lightbulbs is known to follow a right-skewed distribution with mean 24 months and standard deviation 2 months. Suppose that a sample of 52 lightbulbs is taken. What is the probability that the average lifetime of these bulbs is greater than 24.32 months? Answer is 0.1251

5. fill amounts of jars of peanuts from a certain factors are known to follow a Normal distribution with mean 454g and standard deviation 15g. Suppose that a random sample of 8 jars is taken. What is the probability that the average weight of this sample is between 451g and 456g? Answer is 0.3637

A certain statistical test is designed so that it fails 2% of the time. Suppose that 700 of these tests are randomly selected, and we wish to calculate the proportion of these tests that result in a failure. What is the probability that less than 2.5% of these tests end in failure? Answer is 0.8264

Consider the answers you gave in questions 1, 5, and 7. Were these answers exact, or approximate?

Select one:

a. Exact, Approximate, Exact.

b. Exact, Approximate, Approximate.

c. Approximate, Approximate, Approximate.

d. Approximate, Exact, Exact.

e. Approximate, Approximate, Exact.

f. Approximate, Exact, Approximate.

g. Exact, Exact, Approximate.

h. Exact, Exact, Exact.

Answer 1

1)since 1st distribution is not normal it is an approximation

5) it is normally distributed therefore exact

it is normal approximation of binomial distribution, therefore approximation

correct option is :

f. Approximate, Exact, Approximate.