Finding the Fourth Proportional to 89.18, 122.98 and 78.56

Step by Step Solution

1. Step 1: Write the proportion equation
   89.18 : 122.98 = 78.56 : x
2. Step 2: Convert to fraction form
   89.18/122.98 = 78.56/x
3. Step 3: Cross multiply
   89.18x = 122.98 × 78.56
4. Step 4: Simplify right side
   89.18x = 9,661.31
5. Step 5: Solve for x
   x = 9,661.31/89.18
6. Step 6: Final answer
   x = 108.33