Look at this series: 1.5, 2.3, 3.1, 3.9, ...
What number should come next?

Correct option is D

​The given series is: 1.5, 2.3, 3.1, 3.9, ...
1. Notice the difference between consecutive terms:
- 2.3 - 1.5 = 0.8
- 3.1 - 2.3 = 0.8
- 3.9 - 3.1 = 0.8

2. The difference between terms is consistent, with each term increasing by 0.8.

3. Add 0.8 to the last term:
3.9 + 0.8 = 4.7

Thus, the next number in the series is 4.7​