Finding the Fourth Proportional to 100.79, 139.04 and 82.15

Step by Step Solution

1. Step 1: Write the proportion equation
   100.79 : 139.04 = 82.15 : x
2. Step 2: Convert to fraction form
   100.79/139.04 = 82.15/x
3. Step 3: Cross multiply
   100.79x = 139.04 × 82.15
4. Step 4: Simplify right side
   100.79x = 11,421.69
5. Step 5: Solve for x
   x = 11,421.69/100.79
6. Step 6: Final answer
   x = 113.32