sir, lagta hey thodi si galti ho gayi hey.
Total number of subsets is 10C2 = 45.
Number of subsets, where both are of the form 3k is 3C2 = 3
Where one is of the form 3k+1 and the other 3k-1 is 4X3 = 12
So the prob is 1/3
Find the number of 2-subsets of the set {1,2,.....10} , sum of whose elements is divisible by 3.
sir, lagta hey thodi si galti ho gayi hey.
Total number of subsets is 10C2 = 45.
Number of subsets, where both are of the form 3k is 3C2 = 3
Where one is of the form 3k+1 and the other 3k-1 is 4X3 = 12
So the prob is 1/3