Finding the Fourth Proportional to 100.83, 139.08 and 78.96

Step by Step Solution

1. Step 1: Write the proportion equation
   100.83 : 139.08 = 78.96 : x
2. Step 2: Convert to fraction form
   100.83/139.08 = 78.96/x
3. Step 3: Cross multiply
   100.83x = 139.08 × 78.96
4. Step 4: Simplify right side
   100.83x = 10,981.76
5. Step 5: Solve for x
   x = 10,981.76/100.83
6. Step 6: Final answer
   x = 108.91