Question

A box contains 400 black pens and 50 red pens. Jose said the sum of the probability that a randomly selected pen will not be black and the probability that the pen will not be red is 1, P(not black) + P(not red) = 1. Do you agree with him? Complete the explanation to answer the question.

I (disagree/agree) with Jose that the sum of the probability that a randomly selected pen will not be black and the probability that the pen will not be red is 1.

Answer 1

I agree with Jose that the sum of the probability that a randomly selected pen will not be black and the probability that the pen will not be red is 1.

Explanation:

If we sum the probability of not black and probability of not red, we will get 1.

The probability of not black means probability of red i.e 50/450

The probability of not red means probability of black i.e 400/450.

When we add the probability, we get 1.

50/450 + 400/450 = 450/450 = 1

Invariably, the statement is same as finding probability of black and probability of red; just that the value are interchanged.