Finding the Fourth Proportional to 1,009.60, 1,513.69 and 392.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,009.60 : 1,513.69 = 392.78 : x
2. Step 2: Convert to fraction form
   1,009.60/1,513.69 = 392.78/x
3. Step 3: Cross multiply
   1,009.60x = 1,513.69 × 392.78
4. Step 4: Simplify right side
   1,009.60x = 594,549.96
5. Step 5: Solve for x
   x = 594,549.96/1,009.60
6. Step 6: Final answer
   x = 588.90