Probability Study Guide

What is the probability of spinning a number less than 4 on a fair spinner numbered 1-4?

• A) 1/4

• B) 1/2

• C) 3/4

• D) 1

Answer explanation

To spin a number less than 4 on a spinner numbered 1-4, there are 3 favorable outcomes (1, 2, 3) out of 4 total outcomes. Therefore, the probability is 3/4.

What is the probability of spinning a number greater than 4 on a fair spinner numbered 1-4?

• A) 0/4

  0.0

  0%

  Impossible

• B) 1/4

  0.25

  25%

  Unlikely

• C) 1/2

  0.5

  50%

  As equally likely as not

• D) 3/4

  0.75

  75%

  Likely

Answer explanation

The probability of spinning a number greater than 4 on a spinner numbered 1-4 is 0, making it impossible. Therefore, the correct choice is A) 0/4, 0.0, 0%, Impossible.

What is the probability of spinning an even number on a fair spinner numbered 1-4?

• A) 1/4

  0.25

  25%

  Unlikely

• B) 1/2

  0.5

  50%

  Equally likely as not

• C) 3/4

  0.75

  75%

  Likely

• D) 1

  1.0

  100%

  Certain

Answer explanation

The probability of spinning an even number on a fair spinner numbered 1-4 is 2 out of 4 possible outcomes, which simplifies to 1/2 or 0.5, making it equally likely as not.

What does the term "uniform probability" mean?

• A) Each outcome has a different chance of occurring

• B) Each outcome has the same chance of occurring

• C) No outcomes are possible

• D) Outcomes depend on previous events

Answer explanation

Each outcome has the same chance of occurring

What is the probability of not choosing a red candy from a bag containing 30 candies, where 5 are red?

Simplify and read each answer choice

• A) 1/6

  0.167

  16.7%

  Unlikely

• B) 5/30

  0.167

  16.7%

  Unlikely

• C) 25/30

  0.833

  83.3%

  Likely

• D) 5/6

  0.833

  83.3%

  Likely

Answer explanation

Choose not red candy, so probability is 1 - (5/30) = 25/30 = 5/6 = 0.833 = 83.3%. Correct choice is D.

What is the probability of choosing either a green or blue candy from a bag containing 30 candies, where 10 are green and 8 are blue?

• A) 3/5

  0.60

  60%

  Likely

• B) 18/30

  0.60

  60%

  Likely

• C) 2/3

  0.667

  66.7%

  Likely

• D) 3/4

  0.75

  75%

  Likely

Answer explanation

The probability of choosing a green or blue candy is (10 green + 8 blue) / 30 total candies = 18/30 = 3/5, which is equivalent to 0.60 or 60%.

What is theoretical probability?

• What should happen in an experiment

• What actually happens or the outcome.

• A type of statistical method

• A calculation involving only one possible outcome

Answer explanation

What should happen in an experiment

What should be done if experimental probability is not close to theoretical probability?

• Repeat the experiment

• Change the theoretical probability

• Ignore the results

• None of the above

Answer explanation

Repeat the experiment to obtain more data and improve the accuracy of the experimental probability.

Based on theoretical probability, how many times would Jason expect to spin DIME if the spinner is spun 40 times?

• 10 times

• 12 times

• 14 times

• 8 times

Answer explanation

Based on theoretical probability, Jason would expect to spin DIME 10 times out of 40 spins since the probability of landing on DIME is 1/4 (25%) and 1/4 of 40 is 10.