Finding the Fourth Proportional to 82.89, 123.98 and 81.63

Step by Step Solution

1. Step 1: Write the proportion equation
   82.89 : 123.98 = 81.63 : x
2. Step 2: Convert to fraction form
   82.89/123.98 = 81.63/x
3. Step 3: Cross multiply
   82.89x = 123.98 × 81.63
4. Step 4: Simplify right side
   82.89x = 10,120.08
5. Step 5: Solve for x
   x = 10,120.08/82.89
6. Step 6: Final answer
   x = 122.09