Finding the Fourth Proportional to 83.69, 125.56 and 81.86

Step by Step Solution

1. Step 1: Write the proportion equation
   83.69 : 125.56 = 81.86 : x
2. Step 2: Convert to fraction form
   83.69/125.56 = 81.86/x
3. Step 3: Cross multiply
   83.69x = 125.56 × 81.86
4. Step 4: Simplify right side
   83.69x = 10,278.34
5. Step 5: Solve for x
   x = 10,278.34/83.69
6. Step 6: Final answer
   x = 122.82