Finding the Fourth Proportional to 100.80, 139.22 and 73.12

Step by Step Solution

1. Step 1: Write the proportion equation
   100.80 : 139.22 = 73.12 : x
2. Step 2: Convert to fraction form
   100.80/139.22 = 73.12/x
3. Step 3: Cross multiply
   100.80x = 139.22 × 73.12
4. Step 4: Simplify right side
   100.80x = 10,179.77
5. Step 5: Solve for x
   x = 10,179.77/100.80
6. Step 6: Final answer
   x = 100.99