SHOW ALL YOUR WORK
1. A variable X has a distribution which is described by the density curve
shown below:
[4]
a. What proportion of observations of X are less than 5?
b. What proportion of observations is between 2 and 4?
2. A random variable X has a semicircular distribution. What must the
diameter be in order for it be a true density curve? [2]
3. A telemarketing firm in a certain city uses a device that dials
residential telephone numbers in that city at random. Of the first
100 numbers dialed, 51% are unlisted. This is not surprising
because 48% of all residential phone numbers in this city are
unlisted. Explain whether the percentages in bold are either a
statistic or parameter. [1]
4. Let Z follow a standard normal distribution, find the following
proportions:
a. P(Z < 0.10)
b. P(Z > -1.30)
c. P(Z > 2.25)
