Finding the Fourth Proportional to 1,276.83, 1,915.52 and 399.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,276.83 : 1,915.52 = 399.31 : x
2. Step 2: Convert to fraction form
   1,276.83/1,915.52 = 399.31/x
3. Step 3: Cross multiply
   1,276.83x = 1,915.52 × 399.31
4. Step 4: Simplify right side
   1,276.83x = 764,879.51
5. Step 5: Solve for x
   x = 764,879.51/1,276.83
6. Step 6: Final answer
   x = 599.05