Problem 183E

Decide whether a discrete or continuous random variable is the best model for each of the following variables:

(a) The number of cracks exceeding one-half inch in 10 miles of an interstate highway.

(b) The weight of an injection-molded plastic part.

(c) The number of molecules in a sample of gas.

(d) The concentration of output from a reactor.

(e) The current in an electronic circuit.

Solution:

Step 1 of 6:

In this problem we have to decide the given variables are continuous or discrete random variables.

Discrete random variable: a discrete random variable is a variable, which can only take a countable number of values.

continuous random variable: a continuous random variable is a variable whose value is obtained by measuring.