28, 34, 45, 61, 72, ….

Options

A. 78
B. 83
C. 88
D. 80

Explanation

To find the next number in the series 28, 34, 45, 61, 72, we will analyze the differences between consecutive terms.

1. **Identify the first term and the second term**:
- First term: 28
- Second term: 34

2. **Calculate the difference between the first and second terms**:
- Difference = 34 - 28 = 6

3. **Identify the second term and the third term**:
- Second term: 34
- Third term: 45

4. **Calculate the difference between the second and third terms**:
- Difference = 45 - 34 = 11

5. **Identify the third term and the fourth term**:
- Third term: 45
- Fourth term: 61

6. **Calculate the difference between the third and fourth terms**:
- Difference = 61 - 45 = 16

7. **Identify the fourth term and the fifth term**:
- Fourth term: 61
- Fifth term: 72

8. **Calculate the difference between the fourth and fifth terms**:
- Difference = 72 - 61 = 11

9. **Now, let's summarize the differences**:
- First difference: 6
- Second difference: 11
- Third difference: 16
- Fourth difference: 11

10. **Observe the pattern in the differences**:
- The differences are: 6, 11, 16, 11
- The differences themselves seem to follow a pattern where the first difference increases by 5 (from 6 to 11), then by 5 again (from 11 to 16), and then decreases back to 11.

11. **Predict the next difference**:
- Following the pattern, after 11, we can expect the next difference to be 6 (as it seems to alternate).

12. **Calculate the next term**:
- Next term = Last term + Next difference
- Next term = 72 + 6 = 78

Thus, the next number in the series is **78**.