To find the missing fourth number in the group, follow these steps:
1. Determine the total sum of the four numbers:
- The average of the four numbers is given as 24.
- Since the average is the total sum divided by the number of elements, we can write:
[tex]\[
\text{Total Sum} = \text{Average} \times \text{Number of Elements} = 24 \times 4 = 96
\][/tex]
2. Calculate the sum of the first three numbers:
- The first three numbers are 35, 11, and 20.
- Adding them together:
[tex]\[
35 + 11 + 20 = 66
\][/tex]
3. Find the remaining number by subtracting the sum of the first three numbers from the total sum:
- We have the total sum of all four numbers as 96.
- The sum of the first three numbers is 66.
- Therefore, the other number is:
[tex]\[
\text{Other Number} = \text{Total Sum} - \text{Sum of First Three Numbers} = 96 - 66 = 30
\][/tex]
Thus, the other number is 30.
So the correct answer is:
```
30
```
