Geometric Probability and Expected Value

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 and 100 students participate. How many blood donors should the American Red Cross expect to collect from until it gets a donor with Type B blood? 

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

You are a terrible driver. Whenever you drive, there is a 40% chance that you run a red light. What is the probability that you dont run a red light until your 6th drive?

You are a terrible driver. Whenever you drive, there is a 40% chance that you run a red light. You go for a drive 10 times. What is the probability that you run a red light on no more than 6 drives?

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 and 100 students participate. What is the probability that at least 10 of the blood donors has Type B blood? 

A blind taste test will be conducted with 9 volunteers to determine whether people can taste a difference between bottled water and tap water. Each participant will taste the water from two different glasses and then identify which glass he or she thinks contains the tap water. Assuming that people cannot taste a difference between bottled water and tap water, what is the probability that at least 8 of the 9 participants will correctly identify the tap water?

Which is the correct representation of the problem?

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 those clothes. The owner had 275 customers that day. Assuming this was a typical day, what is the expected number of customers who buy specialty clothes? 

• 11 customers

• 25 customers

• 2.5 customers

• Not enough information.

The local Chipotle is running a promotion where each large drink cup has a large pull-off tab that reveals a prize or the message "Try again next time."  Chipotle claims that 25% of the cups have tabs with a  prize.  You visit Chipotle to try to win.  What is the probability that you win on your third visit?

• 0.859

• 0.141

• 0.420

• 0.580

2. A family has three children. Find the probability of having one boy and two girls.