Question

A box contains 150 black pens and 50 red pens. jose said the sum of the probability that a randomly selectedpen will not be black and the probability that the pen will not be red is 1. explain wether you agree.
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Answer 1

Answer:

(red pen) = 50/150 = 1/4

prob(not red) = 3/4

prob(black pen) = 150/200) = 3/4

prob(not black) = 1/4

their sum = 3/4 + 1/4 = 1

Answer 2

Answer:

I don't agree because:

the probability = the favorable number of objects(in this case red pens)/the number of all objects(in this case the number of all pens) => the probability of picking a red pen = 50(the number f red pens)/150 + 50(the number of all pens) => p = 50/200, we can simplify by 10 so > 5/20, and we can simplify again by 5 so > 1/10.

1 : 10 = 0.1 and 0.1 * 100 = 10% (probability)