Finding the Fourth Proportional to 1,085.81, 1,628.72 and 316.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,085.81 : 1,628.72 = 316.31 : x
2. Step 2: Convert to fraction form
   1,085.81/1,628.72 = 316.31/x
3. Step 3: Cross multiply
   1,085.81x = 1,628.72 × 316.31
4. Step 4: Simplify right side
   1,085.81x = 515,185.29
5. Step 5: Solve for x
   x = 515,185.29/1,085.81
6. Step 6: Final answer
   x = 474.47