Finding the Fourth Proportional to 82.83, 123.99 and 81.12

Step by Step Solution

1. Step 1: Write the proportion equation
   82.83 : 123.99 = 81.12 : x
2. Step 2: Convert to fraction form
   82.83/123.99 = 81.12/x
3. Step 3: Cross multiply
   82.83x = 123.99 × 81.12
4. Step 4: Simplify right side
   82.83x = 10,058.07
5. Step 5: Solve for x
   x = 10,058.07/82.83
6. Step 6: Final answer
   x = 121.43