Finding the Fourth Proportional to 99.39, 137.15 and 55.72

Step by Step Solution

1. Step 1: Write the proportion equation
   99.39 : 137.15 = 55.72 : x
2. Step 2: Convert to fraction form
   99.39/137.15 = 55.72/x
3. Step 3: Cross multiply
   99.39x = 137.15 × 55.72
4. Step 4: Simplify right side
   99.39x = 7,642.00
5. Step 5: Solve for x
   x = 7,642.00/99.39
6. Step 6: Final answer
   x = 76.89