Probability Models - Review

60% of the commercials aired on a network from 8 PM to 10 PM are 15 seconds long, 20% are 30 seconds long, and the rest are 60 seconds.  What is the expected length of a commercial?

• 25 seconds
• 26 seconds
• 27 seconds
• 28 seconds

60% of the commercials aired on a network from 8 PM to 10 PM are 15 seconds long, 20% are 30 seconds long, and the rest are 60 seconds.  What is the standard deviation?

• 16.4934 seconds
• 17.4929 seconds
• 18.5321 seconds
• 19.0001 seconds

Decide whether a binomial model applies and explain why or why not.   Counting the number of Democrats, Republicans, and Independents in the school faculty

• Yes, a binomial model applies
• No, there are more than two outcomes.

Decide whether a binomial model applies and explain why or why not.   Counting the number of red gummy bears you get as you take them one at a time from a small bag.

• Yes, a binomial model applies
• No, there are more than two outcomes.
• No, the trials are not independent, the probability of success changes after each trial.

Decide whether a binomial model applies and explain why or why not.   Counting the number of times a waiter drops his tray during his shift.

• Yes, a binomial model applies
• No, there are more than two outcomes.
• No, the probability varies depending on what he carries.

A marksman has 80% accuracy hitting targets at 1,000 yards.  What is the probability that she won't hit the target until her third shot?

• 0.032
• 0.4096
• 0.1369
• 0.7373

A marksman has 80% accuracy hitting targets at 1,000 yards.  What is the probability that she will make exactly 4 of her next 5 shots?

• 0.032
• 0.4096
• 0.1369
• 0.7373

A marksman has 80% accuracy hitting targets at 1,000 yards.  What is the probability that he will make exactly 18 of his next 20 shots?

• 0.032
• 0.4096
• 0.1369
• 0.7373

A marksman has 80% accuracy hitting targets at 1,000 yards.  What is the probability that he will make at least 4 of his next 5 shots?

• 0.032
• 0.4096
• 0.1369
• 0.7373

A marksman has 80% accuracy hitting targets at 1,000 yards.  Find the probability that she will miss exactly 2 of her next 30 shots?

• 0.0337
• 0.4096
• 0.1369
• 0.7373