Finding the Fourth Proportional to 92.80, 139.12 and 38.72

Step by Step Solution

1. Step 1: Write the proportion equation
   92.80 : 139.12 = 38.72 : x
2. Step 2: Convert to fraction form
   92.80/139.12 = 38.72/x
3. Step 3: Cross multiply
   92.80x = 139.12 × 38.72
4. Step 4: Simplify right side
   92.80x = 5,386.73
5. Step 5: Solve for x
   x = 5,386.73/92.80
6. Step 6: Final answer
   x = 58.05