Binomial Review

Which of the following is false about binomial probabilities?

• Their distributions are approximately symmetric.

• Trials must be fixed.

• Events musts be independent.

• The probability of success must be 0.50

Find the standard deviation of a binomial distribution with n=50 and p=0.4 (Round to the nearest tenth)

• 4.2

• 3.5

• 12.0

• 6.2

Which descriptions are true for a binomial distribution?

• the probability of success must be the same for each event

• the probability for each event must be 0.5

• there can be only two possible outcomes

• The probabilities must add to 1

• each trial must be independent

If you were to flip a coin 20 times, what is the probability you would get exactly 10 heads?

• 50%

• 17.62%

• .58.81%

• 41.19%

The American Red Cross says that about 11% of the U.S. population has Type B blood. A blood drive is being held at your school.What is the probability that exactly 2 of the first 20 blood donors have Type B blood? 

• 0.316

• 0.282

• 0.001

• Not here

In Vietnam, the probability of rain is 70%.  Find the probability of it raining at most 2 days in a week.

• .9712

• .0250

• .0287

• .2988

In Vietnam, the probability of rain is 70%.  Find the probability of it raining at most 5 days in a week.

• .9712

• .6705

• .3294

• .5520

A research team at Cornell University conducted a study showing that approximately 10% of all businessmen who wear ties wear them so tightly that they actually reduce blood flow to brain, diminishing cerebral functions. At a board meeting of 20 businessmen, all of whom wear ties, what is the probability that at least one tie is too tight?

• 27.0%

• 12.2%

• 73.0%

• 87.8%

The student who makes the morning announcements has the bad habit of saying “like” all the time. The chance that they say “like” in a sentence is 60%. You decide to keep a tally of how many times they say like. If they say 350 sentences this week, what is the probability that they will say “like” at least 200 times?

• 0.87

• 0.13

• 0.85

• 0.15

Find the mean of a binomial distribution with n=50 and p=0.4

• 50

• 4

• 20

• 10