Geometric and Binomial Random Variable

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. How many blood donors should the American Red Cross expect to collect from until it gets a donor with Type B blood? 

• 9.1 donors
• 8.5 donors
• 10.3 donors
• Cannot be determined.

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 the tenth blood donor is the first donor with Type B blood?

• approximately 0.00
• 0.316
• 0.0385 
• 0.279

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

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 at least 2 of the first 10 blood donors has Type B blood? 

• 0.088
• 0.697
• 0.214
• 0.303 

We calculate the probability of rolling a 6 for the first time on the 6^th roll of a die using the binomial distribution? 

• True
• False

A September 2011 Gallup survey suggests that 38% of Americans are planning on voting for Barack Obama in the 2012 presidential election. Among a random sample of 100 people, approximately how many would you expect to vote for Obama? 

• 38 people
• 42 people
• 6 people
• Cannot be determined

Which of the following is true about geometric distributions?

• Geometric distributions are approximately skewed right.
• Geometric distributions are approximately symmetric.
• Geometric distributions are approximately skewed left.
• The shape could be symmetric or skewed.

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

A test consists of 10 multiple choice questions with five choices for each question.  As an experiment, you GUESS on each and every answer without even reading the questions. 
What is the probability of getting exactly 6 questions correct on this test?

• 0.6%
• 0.00001%
• 0.0064%
• 0.0002%

When rolling a fair die 100 times, what is the probability of rolling a "4"exactly 25 times?

• 0.010
• 0.167
• 0.25
• 0.021