What should come in place of question mark in questions
8.5 10.5 16.5 28.5 48.5 ?

Options

A. 57.5
B. 78.5
C. 93.5
D. 64.5

Answer

To solve the problem, we need to identify the pattern in the given number series: 8.5, 10.5, 16.5, 28.5, 48.5, and find the next number.

### Step-by-Step Solution:

1. **Identify the Differences:**
- Start with the first two numbers:
- \(10.5 - 8.5 = 2\)
- Next, find the difference between the second and third numbers:
- \(16.5 - 10.5 = 6\)
- Then, find the difference between the third and fourth numbers:
- \(28.5 - 16.5 = 12\)
- Finally, find the difference between the fourth and fifth numbers:
- \(48.5 - 28.5 = 20\)

So far, the differences are:
- \(2, 6, 12, 20\)

2. **Identify the Pattern in Differences:**
- Now, let's look at the differences between the differences:
- \(6 - 2 = 4\)
- \(12 - 6 = 6\)
- \(20 - 12 = 8\)

The second level of differences is:
- \(4, 6, 8\)

3. **Predict the Next Difference:**
- The differences \(4, 6, 8\) are increasing by \(2\). Thus, the next difference should be:
- \(8 + 2 = 10\)

4. **Calculate the Next Difference:**
- Now, add this new difference to the last difference we calculated:
- \(20 + 10 = 30\)

5. **Find the Next Number in the Series:**
- Finally, add this new difference to the last number in the series:
- \(48.5 + 30 = 78.5\)

Thus, the number that should come in place of the question mark is **78.5**.

### Final Answer:
**78.5**