Finding the Fourth Proportional to 329.47, 494.20 and 86.00

Step by Step Solution

1. Step 1: Write the proportion equation
   329.47 : 494.20 = 86.00 : x
2. Step 2: Convert to fraction form
   329.47/494.20 = 86.00/x
3. Step 3: Cross multiply
   329.47x = 494.20 × 86.00
4. Step 4: Simplify right side
   329.47x = 42,498.84
5. Step 5: Solve for x
   x = 42,498.84/329.47
6. Step 6: Final answer
   x = 128.99