S= 1,2,3, 20 is to be partitioned into four sets A, B, C and D of equal size. The number of ways it can be done, is

Step-by-step solution

Set S= 1,2,3, , 20 is to be partitioned into four sets of equal size i.e., having 5-5 numbers. The number of ways in which it can be done aligned & = ²⁰ C₅ ¹⁵ C₅ ¹⁰ C₅ ^5 C₅ & = 20! 15! 5! 15! 10! 5! 10! 5! 5! 1= (20!) (5!)^4 aligned