Question

Suppose the numbers from 1 to 30 are arranged in consecutive order. How many different pairs of numbers may be selected if there are at least three numbers between the chosen numbers?

Answer 1

is the pair \((a,b)\) considered same as the pair \((b,a)\) ?

Answer 2

i am not sure

Answer 3

If it is consdiered same, then you may count like this :
\[\color{blue}{1},2,3,4,5,\ldots,26,27,28,29,30\]

If you choose the first number as \(\color{blue}{1}\), how many choices are there for the second number in the pair ?

Answer 4

2

Answer 5

what are they ?