Finding the Fourth Proportional to 99.96, 138.12 and 78.12

Step by Step Solution

1. Step 1: Write the proportion equation
   99.96 : 138.12 = 78.12 : x
2. Step 2: Convert to fraction form
   99.96/138.12 = 78.12/x
3. Step 3: Cross multiply
   99.96x = 138.12 × 78.12
4. Step 4: Simplify right side
   99.96x = 10,789.93
5. Step 5: Solve for x
   x = 10,789.93/99.96
6. Step 6: Final answer
   x = 107.94