1 votes 1 votes I am confused with Following formulaes of combination.. 1. n!/r! 2. n+k-1 C k 3. (P+1)*2^R where (P+R are total things and P are alike). 4. question such as number of ways of choosing 10 balls out of 15 balls in which 5 are red,8 are green,2 are black. Anybody please provide me some reference to understand these formulaes related to combination. Combinatory combinatory + – Ravi_1511 asked Jan 31, 2017 retagged Jun 27, 2017 by Arjun Ravi_1511 344 views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
0 votes 0 votes in your question, 15 balls are divided in colours! but i need to take 10 balls.and no condition is given on the colors of that 10 balls. so i can take any color balls, simply i have to choose 10 balls from 15 balls ,ehich is 15C10 Aboveallplayer answered Jan 31, 2017 Aboveallplayer comment Share Follow See all 3 Comments See all 3 3 Comments reply Ravi_1511 commented Jan 31, 2017 reply Follow Share identical balls will change the way to select .. 0 votes 0 votes Aboveallplayer commented Jan 31, 2017 reply Follow Share yes! the word identical will change 0 votes 0 votes yg92 commented Jan 31, 2017 reply Follow Share @Uddipto does that mean by default we consider the balls as distinc when not mentionedt? 0 votes 0 votes Please log in or register to add a comment.