Finding the Fourth Proportional to 82.51, 123.89 and 81.07

Step by Step Solution

1. Step 1: Write the proportion equation
   82.51 : 123.89 = 81.07 : x
2. Step 2: Convert to fraction form
   82.51/123.89 = 81.07/x
3. Step 3: Cross multiply
   82.51x = 123.89 × 81.07
4. Step 4: Simplify right side
   82.51x = 10,043.76
5. Step 5: Solve for x
   x = 10,043.76/82.51
6. Step 6: Final answer
   x = 121.73