Question

4. Find the standard deviation of the following discrete probability distribution. Round off to two decimal places.

x P(x)

0 0.1

1 0.85

2 0.9-a

5. A die is rolled 7 times. Success is getting a 6. Find the probability of getting three 6's. Round off to three decimal places.

6. A light bulb manufacturer finds that the lifespan of its products is normally distributed with a mean of 800 hours and a standard deviation of 50. Find the probability that 825< x < 875. Round off to four decimal places.

7. A battery manufacturer finds that the life of its batteries is normally distributed with a mean of 32 months and a standard deviation of 5 months. Find the probability that a battery lasts less than 30 months. Round off to four decimal places.

PLEASE SHOW ALL WORK FOR EACH PROBLEM, Thank you

Answer 1

Answer 4)

Variance ( X) = E( ) -

Where

E(X) =

E() =

Solution file is attached go through it

Thanks