Finding the Fourth Proportional to 100.82, 139.14 and 77.47

Step by Step Solution

1. Step 1: Write the proportion equation
   100.82 : 139.14 = 77.47 : x
2. Step 2: Convert to fraction form
   100.82/139.14 = 77.47/x
3. Step 3: Cross multiply
   100.82x = 139.14 × 77.47
4. Step 4: Simplify right side
   100.82x = 10,778.83
5. Step 5: Solve for x
   x = 10,778.83/100.82
6. Step 6: Final answer
   x = 106.91