A box holds 12 green pencils and an unknown number of blue pencils

MATHEMATICS · Single correct · CBSE · Mathematics · Probability · Probability

Problem

A box holds 12 green pencils and an unknown number of blue pencils. If a pencil picked at random is green with probability

\frac{3}{7}

, how many pencils are there in the box altogether? (a) 40 (b) 84 (c) 28 (d) 21