The article “Traps in Mineral Valuations—Proceed With Care” (W. Lonegan, Journal of the Australasian Institute of Mining and Metallurgy, 2001:18–22) models the value (in millions of dollars) of a mineral deposit yet to be mined as a random variable X with probability mass function p(x) given by p(10) = 0.40, p(60) = 0.50, p(80) = 0.10, and p(x) = 0 for values of x other than 10, 60, or 80.
a. Is this article treating the value of a mineral deposit as a discrete or a continuous random variable?
b. Compute μ_X.
c. Compute σ_X.
d. The project will be profitable if the value is more than $50 million. What is the probability that the project is profitable?