Question: A teacher has a box of 20 pens: 10 are blue, 7 are black, and 3 are red. If she randomly selects one pen, what is the probability that it is blue or red?
(A) 1⁄5
(B) 11⁄9
(C) 5⁄7
(D) 13⁄20
Solution:
Total pens = 20.
Number of blue or red pens = 10+3=13.
Thus, the probability is:
P(blue or red)= 13⁄20
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