Grumpy Corp drug tests all of the recent college graduates it hires each year. The drug test currently used correctly determines drug users 96% of the time(a Positive test) and correctly determines non-users 90% of the time(a Negative test). A recent study concluded that 36% of college students use drugs. A potential employee has been tested and the result was Negative for drug use. Required:
a. Construct ALL necessary probabilities using proper notation(Example: P(D) for a "drug user").
b. Find the Probability of a Negative test, by showing use of the above Probabilities first, and then followed by the proper calculation.