What will come in place of question mark (?) in the given number series?
17 9 10 16.5 ? 90

Options

A. 44
B. 35
C. 48
D. 38

Answer

To solve the number series: 17, 9, 10, 16.5, ?, 90, we will analyze the pattern between the numbers step by step.

### Step 1: Analyze the transition from 17 to 9
- We see that 17 is reduced to 9.
- To find the operation, we can multiply 17 by 0.5, which gives us 8.5.
- Then, we add 0.5 to 8.5 to get 9.

**Hint:** Look for a multiplication followed by an addition to see how the numbers change.

### Step 2: Analyze the transition from 9 to 10
- Now, we go from 9 to 10.
- We can see that we add 1 to 9 to get 10.

**Hint:** Sometimes, the operation can be a simple addition.

### Step 3: Analyze the transition from 10 to 16.5
- Next, we move from 10 to 16.5.
- We multiply 10 by 1.5, which gives us 15, and then we add 1.5 to get 16.5.

**Hint:** The multiplication factor is increasing, so keep track of the pattern.

### Step 4: Determine the operation for the next number (?)
- Now, we need to find the next number after 16.5.
- Following the pattern, we will multiply 16.5 by 2 (the next increment in the multiplication factor), which gives us 33.
- Then, we add 2 to 33 to get 35.

**Hint:** Continue the pattern of increasing the multiplication factor and adding an increment.

### Step 5: Verify the final number (90)
- Now, we check the transition from 35 to 90.
- We multiply 35 by 2.5, which gives us 87.5, and then we add 2.5 to get 90.

**Hint:** Always verify that the last number fits the established pattern.

### Conclusion
The number that comes in place of the question mark (?) in the series is **35**.

### Final Answer
**35**