Out of 21 tickets marked with numbers from 1 to 21, three are
drawn at random. Find the probability that the numbers on them are in Arithmetic Progression?
I can understand that there are C(21,3) outcomes.But how many A.P series can be there?
Hello, earthboy!
Out of 21 tickets marked with numbers from 1 to 21, three are drawn at random.
Find the probability that the numbers on them are in Arithmetic Progression
I can understand that there are C(21,3) outcomes.
But how many A.P series can be there?
There is no formula for your question.
I see no choice but to List them and Count them . . . and look for a pattern.
Sequences beginning with 1: .
Sequences beginning with 2: .
Sequences beginning with 3: .
. . . . . . . . . . . . . . . . . . . . . . . . . .
Sequences beginning with 17:.
Sequences beginning with 18:.
Sequences beginning with 19:.
Do you see a pattern?