Which of the following is a continuous random variable?

1.   ?    The number of people joining a post office queue in a 5-minute interval
2.   ?    The number of attempts a person has before they pass their driving test
3.   ?    The total amount of weight lost by a group of dieters
4.   ?    Alcoholic beverages sold at a particular bar

What does the abbreviation pdf stand for in relation to a continuous random variable?

1.   ?    Probability density function
2.   ?    Probability dependent function
3.   ?    Partially described formula
4.   ?    Population distribution function

Which of the following is NOT an attribute of a pdf?

1.   ?    Its curve lies on or above the x axis
2.   ?    Its curve is symmetric
3.   ?    The area under the whole curve is 1
4.   ?    The area under the curve between a and b is P(a< X <b)

A random variable, X, can take values between 0 and 1 and has the pdf f(x) = 2x. What is the probability that X is smaller than 0.5?

1.   ?    0.1
2.   ?    0.75
3.   ?    0.5
4.   ?    0.25

The time (in minutes) between phone calls at a computing help desk is known to have an exponential distribution with mean 2 minutes.
What is the probability that there is less than one minute between calls?

1.   ?    0.3935
2.   ?    0.632
3.   ?    0.5
4.   ?    0.6065

If Z has a standard normal distribution, what is P(Z < 1)?

1.   ?    0.5
2.   ?    0.5398
3.   ?    0.8413
4.   ?    0.1587

If X is normally distributed with standard deviation 1 and P(X < 5) = 0.0228, what is the mean of X?

1.   ?    10
2.   ?    7
3.   ?    12
4.   ?    8

The amount a customer spends at a single visit to PCExtra is normally distributed with a mean of £150 and a variance of £625. It wishes to offer a reward to the 10% of customers who spend the most. How much must customers spend to be eligible for the reward?

1.   ?    £182
2.   ?    £175
3.   ?    £190
4.   ?    £192

A random variable, X, comes from a binomial distribution with n = 60 and p = 0.2. Calculate (approximately) P(X ≤ 20)?

1.   ?    0.8413
2.   ?    0.5842
3.   ?    0.9969
4.   ?    0.3333

If X has a binomial n, p distribution, which of the following is NOT required in order for the normal approximation to the binomial to be appropriate?

1.   ?    n(1-p) ≤; 5
2.   ?    np ≤ 5
3.   ?    n must be large
4.   ?    p ≤ 0.4