Finding the Fourth Proportional to 92.88, 128.28 and 78.18

Step by Step Solution

1. Step 1: Write the proportion equation
   92.88 : 128.28 = 78.18 : x
2. Step 2: Convert to fraction form
   92.88/128.28 = 78.18/x
3. Step 3: Cross multiply
   92.88x = 128.28 × 78.18
4. Step 4: Simplify right side
   92.88x = 10,028.93
5. Step 5: Solve for x
   x = 10,028.93/92.88
6. Step 6: Final answer
   x = 107.98