3/20, 3/10, 9/20, 3/5 ...

Find terms of an arithmetic sequence.

What's the next fraction in this sequence? Simply your answer.

3/20, 6/20, 9/20, 12/20 so the common difference is 3/20, ie each term is 3/20 greater than the term preceding it. Any arithmetic sequence can be expressed as:

a (n) = a+d (n-1), a=initial term, d=common difference, n=term number, in this case:

a (n) = 3/20 + (3/20) (n-1)

a (n) = 3/20+3n/20-3/20

a (n) = 3n/20 so the 5th term is:

a (4) = 3*5/20=15/20=3/4