Probability Distribution Review

Find the expected value (mean) of the distribution.

• 1

• 2.45

• 0.6125

• unable to determine

The car company chooses a sample of 50 ball bearings from the shipment. If they find more than 2 defective bearings, the shipment is rejected. It is a fact that the factory produces 4% defective bearings.

What is the probability that the sample is clear of defects?

• 0.271

• 0.130

• 0.002

A policeman inspected the safety of tyres on cars passing through a checkpoint. 

The number of tyres X which needed replacing on each car followed the probability distribution shown.

Find the value of k.

• 0.04

• 0.4

• 0

P(X > 1) = 0.6 could mean . . .

• The probability that there is less than 1 head is 60%

• The probability that there is more than 1 head is 60%

• The probability that there is more than 60 heads is 1

Which is the correct notation for the following: The mass, W, of bags of rice follows a normal distribution with mean 1000 g & standard deviation 4 g.

The mass, W, of bags of rice follows a normal distribution with mean 1000 g & standard deviation 4 g.

     92% of the bags of rice have a mass more than k grams.

Find the value of k  .

• 994

• 1005

• 1

• 0

• 60.6

• 0.420

• 9.91%

• 60.6%

Use the probability distribution table to answer the question. What is P(X≥2)?

• 0.12

• 0.21

• 0.8

Trina has two spinners. One Spinner has 4 equal sections that are numbered 1-4. The other spinner has 5 equal sections that are numbered 1-5. Trina spins both spinners at the same time.

       The random variable X is the sum of the numbers on which the spinners land. What is P(5 ≤X≤8)?

The masses of the oranges on sale at a farm stand are normally distributed with a mean of 239 grams and a standard deviation of 25 grams. What is the z-score of an orange that has a mass of 259 grams. (Use the drawing tools to show your work.)