SOLUTION: A discrete random variable X has the probability mass function P(x) = 4x-x^2/a for x = 0, 1, 2, 3. What is the value of a? Ans: a=10. How do I solve this, please explain!

Question 1189200: A discrete random variable X has the probability mass function P(x) = 4x-x^2/a for x = 0, 1, 2, 3. What is the value of a?
Ans: a=10. How do I solve this, please explain!
Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

I can tell you how to solve it; but I can't show you the solution because I don't know what the function is.

Is it 4x-x^2/a = ?

Or is it (4x-x^2)/a = ?

If your mathematical education is to the point where you are working on a problem like this, you should know by now that parentheses are important....

HOW to solve it is easy: the sum of all the probabilities must be 1: P(0)+P(1)+P(2)+P(3)=1

Whatever the function is, evaluate it for each value of x and solve that equation to find the value of a.

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