Finding the Fourth Proportional to 86.69, 130.21 and 82.91

Step by Step Solution

1. Step 1: Write the proportion equation
   86.69 : 130.21 = 82.91 : x
2. Step 2: Convert to fraction form
   86.69/130.21 = 82.91/x
3. Step 3: Cross multiply
   86.69x = 130.21 × 82.91
4. Step 4: Simplify right side
   86.69x = 10,795.83
5. Step 5: Solve for x
   x = 10,795.83/86.69
6. Step 6: Final answer
   x = 124.53