Finding the Fourth Proportional to 83.57, 124.56 and 81.09

Step by Step Solution

1. Step 1: Write the proportion equation
   83.57 : 124.56 = 81.09 : x
2. Step 2: Convert to fraction form
   83.57/124.56 = 81.09/x
3. Step 3: Cross multiply
   83.57x = 124.56 × 81.09
4. Step 4: Simplify right side
   83.57x = 10,100.57
5. Step 5: Solve for x
   x = 10,100.57/83.57
6. Step 6: Final answer
   x = 120.86