Question 7 An urn contains 6 balls of which two are red and four are black. Two balls are drawn at random. Probability that they are of the different colours is (a) 2/5 (b) 1/15 (c) 8/15 (d) 4/15
P(they are of different colors)
= P(first ball drawn is black) × P(second ball drawn is red)
+ P(first ball drawn is red) × P(second ball drawn is black)
= 4/6 × 2/5 + 2/6 × 4/5
= 8/30+8/30
= 16/30
= 𝟖/𝟏𝟓
∴ The correct answer is (c) = 8/15
1 mark
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.