A bag contains 4 red, 6 green, and 5 blue balls. One ball is drawn at random. Find (i) the probability of drawing a green ball and (ii) the probability of not drawing a red ball.

hard 4 marks Class 7 · Mathematics · Data Handling

Answer

2/5 and 11/15

The correct answer is 2/5 and 11/15 — (ii) Balls that are not red: $6 + 5 = 11$ . Probability $= \frac{11}{15}$ (Complementary event).

Step-by-step solution

Count total balls: $4 + 6 + 5 = 15$ (Total outcomes).
(i) Count favourable outcomes for green: 6. Probability $= \frac{6}{15} = \frac{2}{5}$ (Simplify the fraction).
(ii) Balls that are not red: $6 + 5 = 11$ . Probability $= \frac{11}{15}$ (Complementary event).

Common mistake: Miscounting total or favourable outcomes

Concept tested: Probability of discrete events