Which one of these variables is a binomial random variable?

Which one of these variables is a binomial random variable?
 a. Time it takes a randomly selected student to complete a multiple choice exam.
  b. Number of textbooks a randomly selected student bought this term.
  c. Number of women taller than 68 inches in a random sample of 5 women.
  d. Number of CDs a randomly selected person owns.

Q. 2

An Anti-Smoking organization wishes to determine what percentage of students in the state of Pennsylvania smoke cigarettes at least once a day. The organization will randomly sample 2400 students. In the sample they obtain, 450 students say they smoke cigarettes at least once a day. Calculate a 95 confidence interval for the proportion of all students in the state of Pennsylvania that smoke cigarettes at least once a day.

Q. 3

Which one of these X' variables is a discrete random variable?
 a. An experiment in chemistry is repeated many times and X is the time required for a reaction to occur in seconds.
  b. A student is randomly selected and X is the number of correct answers on a two question multiple-choice quiz.
  c. A UPS package is randomly selected and X is the weight in pounds of the package.
  d. A student is randomly selected and X is the distance they must travel in feet to go from their dorm room door to the door of their first class on Monday morning.

Q. 4

In a randomly selected sample of 500 students at a University, 80 say they plan to graduate within 4 years. Calculate a 95 confidence interval for the proportion of all students who plan to graduate within 4 years.

Q. 5

Which one of these variables is a continuous random variable?
 a. The time it takes a randomly selected student to complete an exam.
  b. The number of tattoos a randomly selected person has.
  c. The number of women taller than 68 inches in a random sample of 5 women.
  d. The number of correct guesses on a multiple choice test.

Q. 6

In a randomly selected sample of 100 students at a University, 85 had use of a laptop computer. Calculate a 99 confidence interval for the proportion of all students who had use of a laptop computer.