Binomial Random Variables

True or False:
exactly = binompdf
at most = binomcdf
at least = 1-binomcdf  

• True
• False

True or False:

When I see the word at least I must remember to reduce the number following at least by 1.

at least 4

1-binomcdf (10, 0.25, 3)

• True

• False

MC test with 4 choices per question. Find probability of getting EXACTLY 5 out of 12 questions correct. Which of the following is used to find the probability?

• binompdf(12, .25, 5)

• binomcdf(12, .25, 5)

• 1−binomcdf(12, .25, 5)

• 1-binompdf(12, .25, 5)

MC test with 4 choices per question find probability of getting AT MOST 5 out of 10 questions correct. Which of the following would be used?

• binompdf(10, .25, 5)

• binomcdf(10, .25, 5)

• 1−binomcdf(10, .25, 5)

• 1-binomcdf(10, .25, 4)

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

• .9712

• 0.0250

• .0288

• .2988

If a standard die is rolled 8 times, find the probability of rolling a number 4 at least twice.

• .3953
• .9548
• .8554
• .2245

The probability of winning is 1/3. Bob plays 6 games. Find P(win at least 3 games):

• P(X=0)+P(X=1)+P(X=2)+P(X=3)

• binompdf(6, 1/3, 3)

• 1-binomcdf(6, 1/3, 3)

• 1-binomcdf(6, 1/3, 2)

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 of the following is NOT an assumption of the Binomial distribution?

• All trials must be independent.
• Each trial must be classified as a success or a failure.
• All trials are dependent on each other.
• The number of successes in the trials is counted.

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