Finding the Fourth Proportional to 315,128.56, 472,620.86 and 90,487.21

Step by Step Solution

1. Step 1: Write the proportion equation
   315,128.56 : 472,620.86 = 90,487.21 : x
2. Step 2: Convert to fraction form
   315,128.56/472,620.86 = 90,487.21/x
3. Step 3: Cross multiply
   315,128.56x = 472,620.86 × 90,487.21
4. Step 4: Simplify right side
   315,128.56x = 42,766,143,009.20
5. Step 5: Solve for x
   x = 42,766,143,009.20/315,128.56
6. Step 6: Final answer
   x = 135,710.15