Finding the Fourth Proportional to 100.82, 139.10 and 57.14

Step by Step Solution

1. Step 1: Write the proportion equation
   100.82 : 139.10 = 57.14 : x
2. Step 2: Convert to fraction form
   100.82/139.10 = 57.14/x
3. Step 3: Cross multiply
   100.82x = 139.10 × 57.14
4. Step 4: Simplify right side
   100.82x = 7,948.17
5. Step 5: Solve for x
   x = 7,948.17/100.82
6. Step 6: Final answer
   x = 78.84