Finding the Fourth Proportional to 82.16, 123.32 and 81.71

Step by Step Solution

1. Step 1: Write the proportion equation
   82.16 : 123.32 = 81.71 : x
2. Step 2: Convert to fraction form
   82.16/123.32 = 81.71/x
3. Step 3: Cross multiply
   82.16x = 123.32 × 81.71
4. Step 4: Simplify right side
   82.16x = 10,076.53
5. Step 5: Solve for x
   x = 10,076.53/82.16
6. Step 6: Final answer
   x = 122.64