An urn contains 5 red and 5 black balls. A ball is drawn at random, its colour is noted and is returned lo the urn. Moreover, 2 additional balls of the colour drawn are put in lhe urn and then a ball is drawn at random. What is the probability that the second ball is red?
.: Required probability $= P$
(second ball is red)
$= P$
(a red ball is drawn and returned along with 2 red balls and then a red ball is drawn $+ P$
(a black ball is drawn and returned along with 2 black balls and then a red ball is drawn)
NCERT & Exemplar solution for CBSE Class 12 Mathematics, Probability. Curated by Sachin Sharma. Free for all students.