Binomial vs. Geometric Settings

If we want to calculate the probability of rolling a 6 for the first time on the 6^th roll of a die, would we use the geometric or the binomial distribution?

• geometric

• binomial

When rolling a fair die 100 times, what is the probability of rolling a "4" exactly 25 times? Is this an example of binomial or geometric?

• binomial

• geometric

If you want to know how many trials you will need before your first success, use the ????? model.

• Geometric

• Binomial

• Normal

• Calculator

If you want a certain number of successes in a set amount of trials, use the ????? model.

• geometric

• binomial

• normal

• calculator

Suppose that a quiz consists of 20 True-False questions. A student hasn't studied for the exam and will just randomly guesses at all answers (with True and False equally likely). How would you find the probability that the will student get 8 or fewer answers correct?

• Find the area between 0 and 8 in a uniform distribution that goes from 0 to 20.

• Find the probability that X=8 for a normal distribution with mean of 10 and standard deviation of √5

• Find the cumulative probability for 8 in a binomial distribution with n = 20 and p = 0.5.

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

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

A restaurant offers a game piece with each meal to win coupons for free food. The probability of a game piece winning is 1out of 4 and is independent of other game pieces winning. A family orders 4 meals. Let C be the number of coupons the family wins.

What type of variable is C?

• Geometric

• Binomial

• Both

• Neither

Alma wrote a phone app. She has noticed that 3% of the users who download her app upgrade it the same day. Let N be the number of customers who download Alma's app until one upgrades it on the same day. Assume that the probability of each user's upgrades are independent.

What type of variable is N?

• Geometric

• Binomial

• Both

• Neither

Leo selects 25 grandparents at random from his town to interview. In the town, 35% of the grandparents have their grandchildren living with them. Let G be the number of grandparents Leo interviews whose grandchildren are living with them.

What type of variable is G?

• Geometric

• Binomial

• Both

• Neither