Identify the type of sequence 1/10, 3/20, 5/30, 7/40 ...

a) geometric sequence

b) arithmetic sequence

c) neither

Arithmetic sequence: must have a constant common difference.

3/20-1/10 = (3-2) / 20=1/20

5/30-3/20 = (10-9) / 60=1/60

Difference is not constant, so no.

Geometric sequence: must have a common ratio

30/20 / (1/10) = 15

5/30 / (3/20) = 100/90 = 10/9

ratio is not constant, so no.

The answer is (c) neither geometric nor arithmetic