CBSE 10th Class past year question paper
Year 2019
SET 1, Code Number- 30/2/1
Question number – 9
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P(blue marble) = 1/5
P(black marble) = 1/4
∴ P(green marble) = 1 – ( (1/5) + (1/4))
= 11/20
Let total number of marbles be X
then,
(11/20) × X = 11
X = 20