Finding the Fourth Proportional to 99.56, 137.25 and 78.81

Step by Step Solution

1. Step 1: Write the proportion equation
   99.56 : 137.25 = 78.81 : x
2. Step 2: Convert to fraction form
   99.56/137.25 = 78.81/x
3. Step 3: Cross multiply
   99.56x = 137.25 × 78.81
4. Step 4: Simplify right side
   99.56x = 10,816.67
5. Step 5: Solve for x
   x = 10,816.67/99.56
6. Step 6: Final answer
   x = 108.65