Finding the Fourth Proportional to 89.17, 122.72 and 78.77

Step by Step Solution

1. Step 1: Write the proportion equation
   89.17 : 122.72 = 78.77 : x
2. Step 2: Convert to fraction form
   89.17/122.72 = 78.77/x
3. Step 3: Cross multiply
   89.17x = 122.72 × 78.77
4. Step 4: Simplify right side
   89.17x = 9,666.57
5. Step 5: Solve for x
   x = 9,666.57/89.17
6. Step 6: Final answer
   x = 108.41