Finding the Fourth Proportional to 100.83, 139.15 and 61.48

Step by Step Solution

1. Step 1: Write the proportion equation
   100.83 : 139.15 = 61.48 : x
2. Step 2: Convert to fraction form
   100.83/139.15 = 61.48/x
3. Step 3: Cross multiply
   100.83x = 139.15 × 61.48
4. Step 4: Simplify right side
   100.83x = 8,554.94
5. Step 5: Solve for x
   x = 8,554.94/100.83
6. Step 6: Final answer
   x = 84.85