Finding the Fourth Proportional to 1,086.28, 1,629.42 and 316.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.28 : 1,629.42 = 316.78 : x
2. Step 2: Convert to fraction form
   1,086.28/1,629.42 = 316.78/x
3. Step 3: Cross multiply
   1,086.28x = 1,629.42 × 316.78
4. Step 4: Simplify right side
   1,086.28x = 516,167.67
5. Step 5: Solve for x
   x = 516,167.67/1,086.28
6. Step 6: Final answer
   x = 475.17