How do I approach this problem?

[thejoeynavarro]

A new study of the medications had the following test groups: People who received neither Pill A nor Pill B People who received one of the two pills People who received both pills Overall, 20% of subjects received neither pill, 20% received only pill A, 20% received only pill B, and 40% received both pills. X is the random variable indicating how many pills each individual is assigned to take.



What is the expected value of X, E[X]? Provide your answer as a number rounded to 1 place (e.g., 1.2 or -1.2).

 

[Dr.Peterson]

You can start by looking up the definition of expected value in your textbook or notes.

The next thing I myself would do is to put the data into a table form, listing each possible case, the value of X (the number of pills), and the probability:

Outcome ..... X ... P(X)
Neither ..... 0 ... 0.20
Pill A only . 1 ... 0.20
Pill B only . 1 ... 0.20
Both pills .. 2 ... 0.40

You might prefer a table that lists only the values of X and their probabilities:

X ... P(X)
0 ... ?
1 ... ?
2 ... ?

Now apply the definition. If you need help, please state the definition you have been taught, and make an attempt to apply it, so we can see how you are thinking.