A bag contains red balls and black balls in the ratio 3 : 7. A ball is drawn at random. The probability that…

Question

A bag contains red balls and black balls in the ratio 3 : 7. A ball is drawn at random. The probability that ball so drawn is black in colour, is

Accepted Answer

## Model Answer **Option C: 0.7** Ratio of red : black = 3 : 7, so total parts = 10. P(black) = 7/10 = **0.7**. Source: Chapter 14, Section 14.1 --- ## Explanation Total balls = 3 + 7 = 10 parts. Favourable outcomes (black) = 7. P(black) = 7/10 = 0.7. Note that 3/7 is the *ratio* of red to black, not a probability — a common mistake to avoid.

Mathematics — CBSE Class 10 board question