Question

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

a) geometric sequence
b) arithmetic sequence
c) neither

Answer 1

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