Finding the Fourth Proportional to 100.83, 139.15 and 57.17

Step by Step Solution

1. Step 1: Write the proportion equation
   100.83 : 139.15 = 57.17 : x
2. Step 2: Convert to fraction form
   100.83/139.15 = 57.17/x
3. Step 3: Cross multiply
   100.83x = 139.15 × 57.17
4. Step 4: Simplify right side
   100.83x = 7,955.62
5. Step 5: Solve for x
   x = 7,955.62/100.83
6. Step 6: Final answer
   x = 78.90