Out of (2n+1) tickets consecutively numbered , three are drawn at random . The chance that the numbers on them are in A.P is

Out of 7 tickets consecutively numbered 3 are drawn at random. The probability for the numbers on the tickets to be in A.P. is

Out of 21 tickets numbered 10, 11, 12,…, 30, three tickets are drawn at random. Find the probability that the numbers on these tickets are in A.P.

Out of 30 consecutive integers two are drawn at random. Then what is the probability that their sum is odd.

Out of 3n consecutive integers, three are selected at random. Show that the chance that their sum is divisible by 3 is (3n^(2)-3n+2)/((3n-1)(3n-2))

Out of 30 consecutive integers, three integers are drawn at random. Find the probability that their sum is (i) an odd number (ii) an even number