Section 4.1 and 4.2 Probability

The probability based on frequency of outcomes during an experiment

•  experimental probability
• fundamental counting principle
• mutually exclusive event
• dependent event

You flip a nickel three times.
Find the probability that all flips will land on tails.

• 1/2
• 1/4
• 1/6
• 1/8

The probability of an event occurring, P(A), can be expressed as a fraction, decimal, or percent.

• True
• False

What is the complement of spinning purple on this spinner?

• Not green
• Purple
• Not purple
• Orange, red, or yellow

Event A has a probability of 0.3. What is the probability of the complement of Event A?

• 30%
• 3/100
• 7/100
• 0.7

Given that the New Jersey Transit claims that its 8am train from Princeton to New York has a probability 0.9 of arriving on time. What does this probability mean in this setting

• If chance behavior is predictable in the long term, then 10% of the trains are never late.

• If you take a very large random sample of the 8am trains from Princeton to New York, about 90% of them will be on time.

• 90% of all the trains from Princeton to New York are on time.

• 90% of the time, the 8am trains from Princeton to New York are never late.

The NJT claims that its 8am train from Princeton to New York has a probability 0.9 of arriving on time. The 8am train has arrived on time 5 days in a row. What's the probability that it will arrive on time tomorrow?

• It will be on time tomorrow, since it's on time 90% of the time.

• The probability of all trains from Princeton to New York is 90%, so this train will be on time. A single train on-time doesn't change the probability of all trains.

• The probability that the 8am train from Princeton to New New is on time tomorrow is still 90%. Any short run of on-time trains does not change the probability that the next train will be on time.

• The probability will change if the train is late, therefore the probability will either increase or decrease.

Events A & B cannot both occur at the same time. For example, we cannot choose an American adult at random who has both high cholesterol and borderline cholesterol. The events are considered to be ...

• Independent Events

• Equally Likely Events

• Mutually Exclusive Events

• Complements

Four events, A, B, C, and D each have the following probabilities in order: P(A) = 0.38, P(B) = 0.25, P(C) = 0.25, and P(D) = 0.10. Is this a valid probability model? Explain.

• Yes, because the sum of the probabilities equals 1.0.

• Yes, because the product of the probabilities is 0.00285.

• No, because the product of probabilities is 0.00285.

• No, because the sum of probabilities does not equal 1.0.

If two events A and B are mutually exclusive, and P(A) = 0.38, and P(B) = 0.25, what is the P(A U B)?

• P(A U B) = P(A) + P(B) - P(A and B)

• P(A U B) = P(A) - P(B)

• P(A U B) = P(A) + P(B)

• P(A U B) = P(A) x P(B)