Geometric and Binomial Distributions

An algebra 2 test has 6 multiple choice questions with four choices with one correct answer each. If we just randomly guess on each of the 6 questions, what is the probability that you get exactly 3 questions correct?

• 0.962

• 0.132

• 0.831

• 0.250

Bob is taking a 100 question test.  They have a 90 % probability of getting any one question correct.  WHICH IS THE CORRECT FORMULA TO FIND OUT THE PROBABILITY that they will answer EXACTLY 70  questions correctly?

• ₁₀₀C₇₀   ( 0.18  )³⁰ ( 0.90  )⁷⁰
  
• ₁₀₀C₇₀   ( 0.10  )³⁰ ( 0.90  )⁶⁰
• ₁₀₀C₇₀   ( 0.10  )³⁰ ( 0.90  )⁷⁰
• ₉₉C₇₀   ( 0.10  )³⁰ ( 0.90  )⁷⁰

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

• 50

• 4

• 20

• 10

Is this binomial experiment? Shuffle a deck of 52 cards. Turn over the top card. Put the card back in the deck, shuffle again. Repeat the process 50 times. Let X = the number of aces you observe.

• Yes
• No, the trials are not independent.
• No, there are more than 2 outcomes

Which one of these variables is a binomial random variable?

• Time it takes a randomly selected student to complete a multiple choice exam
• Number of textbooks a randomly selected student bought this term 
• Number of women taller than 68 inches in a random sample of 5 women
• Number of CDs a randomly selected person owns

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

X ~ B(15, 0.6)

Find P(X = 12)

• 0.06

• 0.13

• 0.87

• 0.94

X is the number of heads when a fair coin is flipped 12 times

Find P(X = 4)

• 0.12

• 0.19

• 0.81

• 0.93

10% of people are left handed. If you select 30 people at random, find the probability that exactly 3 of them are left handed.

• 0.3

• 0.236

• 0.647

• 0.187

10% of people are left handed. If you select 300 people at random, which formula would find the standard deviation of the number of left handed people?

• 300(.1)