Geometric Distribution

The McDonald's Monopoly game has a 1 in 4 chance of winning.  What is the probability your first win is on your third attempt?

• .1406

• .0156

• .2500

• .0352

Only 4% of people have type AB blood.  What is the probability the first person with AB blood at the blood drive will be the 12th donor?

• .0001

• .0255

• .6382

• .2553

Given 13% of people are left-handed.  What is the probability the first left-handed person will be the sixth person polled?  

• .0564

• .1116

• .0001

• .0648

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 owner of a pet store is trying to decide whether to discontinue selling specialty clothes for pets. She suspects that only 4% of the customers buy specialty clothes for their pets. What is the probability that she does NOT sell a garment until the 7th customer? Assume each customer is independent.

• 0.033

• 0.027

• 0.0313

• 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. 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.

Which of the following trials is geometric?

• the number of text messages until you get one from your mom

• the number of text messages that your mom sent

• the number of times the phones rings in a day

• The number of texts in a row that your mom sent

According to the BMV, about 93% of all people who take the driving test pass.  What is the probability it will take someone more than two times to pass the test?

• .9300

• .0651

• .9951

• .0049

To find the mean/expected value for a geometric random variable

• Multiply the number of trials times the probability of success on each trial.

• Divide 1 by the probability of success on each trial.

• Multiply the number of trial times the probability of failure on each trial.

• Divide 1 by the probability of failure on each trial.

Is this a geometric setting?: Shake a bag of 30 marbles, with 10 red marbles, 10 blue marbles, and 10 green marbles. Reach into the bag and pull out a marble. Put the marble back in the bag and shake again. Repeat until you get a green marble. Let G=The number of trials until you get a green marble

• No, there is a set number of trials

• Yes, this successfully satisfies the conditions

• No, the trials are not independent

• No, there are no binary outcomes