Finding the Fourth Proportional to 91.92, 137.22 and 78.18

Step by Step Solution

1. Step 1: Write the proportion equation
   91.92 : 137.22 = 78.18 : x
2. Step 2: Convert to fraction form
   91.92/137.22 = 78.18/x
3. Step 3: Cross multiply
   91.92x = 137.22 × 78.18
4. Step 4: Simplify right side
   91.92x = 10,727.86
5. Step 5: Solve for x
   x = 10,727.86/91.92
6. Step 6: Final answer
   x = 116.71