Finding the Fourth Proportional to 99.72, 137.58 and 56.05

Step by Step Solution

1. Step 1: Write the proportion equation
   99.72 : 137.58 = 56.05 : x
2. Step 2: Convert to fraction form
   99.72/137.58 = 56.05/x
3. Step 3: Cross multiply
   99.72x = 137.58 × 56.05
4. Step 4: Simplify right side
   99.72x = 7,711.12
5. Step 5: Solve for x
   x = 7,711.12/99.72
6. Step 6: Final answer
   x = 77.33