Finding the Fourth Proportional to 1,085.38, 1,628.34 and 315.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,085.38 : 1,628.34 = 315.88 : x
2. Step 2: Convert to fraction form
   1,085.38/1,628.34 = 315.88/x
3. Step 3: Cross multiply
   1,085.38x = 1,628.34 × 315.88
4. Step 4: Simplify right side
   1,085.38x = 514,351.90
5. Step 5: Solve for x
   x = 514,351.90/1,085.38
6. Step 6: Final answer
   x = 473.89