Finding the Fourth Proportional to 90.72, 125.15 and 86.47

Step by Step Solution

1. Step 1: Write the proportion equation
   90.72 : 125.15 = 86.47 : x
2. Step 2: Convert to fraction form
   90.72/125.15 = 86.47/x
3. Step 3: Cross multiply
   90.72x = 125.15 × 86.47
4. Step 4: Simplify right side
   90.72x = 10,820.98
5. Step 5: Solve for x
   x = 10,820.98/90.72
6. Step 6: Final answer
   x = 119.28