Question

1. Suppose that the length of time a particular type of battery lasts follows an exponential distribution with a mean of 25.0 days.

Find the probability that the average time a sample of 49 batteries lasts is at most 24.7 days

a. 0.4665

b. 0.3723

c. 0.6277

d. 0.5335

2. Suppose that the length of time a particular type of battery lasts follows an exponential distribution with a mean of 25.0 days.

Suppose the length of time a battery lasts is collected for a random sample of 49 batteries. Find the distribution for the average length of time a battery operates for the sample of 49 batteries.

a. N(25,25)

b. N(25,3.57)

c. Exp(0.4)

d. Exp(25)

3. Suppose that the length of time a particular type of battery lasts follows an exponential distribution with a mean of 25.0 days.

Find the probability that one randomly selected battery lasts at least 25.8 days.

a. 0.6205

b. 0.3563

c. 0.6437

d. 0.3795

4. Suppose that the length of time a particular type of battery lasts follows an exponential distribution with a mean of 25.0 days.

Find the 25th percentile for the length of time one of this particular type of battery lasts.

a. 0.1 days

b. 7.2 days

c. 6.3 days

d. 8.1 days

5. A multiple choice test consists of 9 questions with 5 choices for each answer, with exactly one correct answer for each question. Assume that a student guesses all questions randomly. Let X = the number of questions a student guesses correctly.

Over the long run of taking such an exam, on average how many questions would you expect a student to get correct by guessing randomly on each question on the test?

a. 1.8

b. 2.2

c. 2

d. 1

Answer 1

Here n=49.

Ans for Q2: N(25, 3.57)

Ans for Q2: 0.4665

Ans for Q3: 0.3563

Ans for Q4: 7.2

Note : As per Chegg policy, one question can be answered per one post.