Finding the Fourth Proportional to 93.17, 128.72 and 78.86

Step by Step Solution

1. Step 1: Write the proportion equation
   93.17 : 128.72 = 78.86 : x
2. Step 2: Convert to fraction form
   93.17/128.72 = 78.86/x
3. Step 3: Cross multiply
   93.17x = 128.72 × 78.86
4. Step 4: Simplify right side
   93.17x = 10,150.86
5. Step 5: Solve for x
   x = 10,150.86/93.17
6. Step 6: Final answer
   x = 108.95