Finding the Fourth Proportional to 91.92, 137.98 and 78.48

Step by Step Solution

1. Step 1: Write the proportion equation
   91.92 : 137.98 = 78.48 : x
2. Step 2: Convert to fraction form
   91.92/137.98 = 78.48/x
3. Step 3: Cross multiply
   91.92x = 137.98 × 78.48
4. Step 4: Simplify right side
   91.92x = 10,828.67
5. Step 5: Solve for x
   x = 10,828.67/91.92
6. Step 6: Final answer
   x = 117.81