Finding the Fourth Proportional to 100.82, 139.16 and 71.79

Step by Step Solution

1. Step 1: Write the proportion equation
   100.82 : 139.16 = 71.79 : x
2. Step 2: Convert to fraction form
   100.82/139.16 = 71.79/x
3. Step 3: Cross multiply
   100.82x = 139.16 × 71.79
4. Step 4: Simplify right side
   100.82x = 9,989.94
5. Step 5: Solve for x
   x = 9,989.94/100.82
6. Step 6: Final answer
   x = 99.09