Finding the Fourth Proportional to 1,042.72, 1,564.42 and 393.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,042.72 : 1,564.42 = 393.50 : x
2. Step 2: Convert to fraction form
   1,042.72/1,564.42 = 393.50/x
3. Step 3: Cross multiply
   1,042.72x = 1,564.42 × 393.50
4. Step 4: Simplify right side
   1,042.72x = 615,599.27
5. Step 5: Solve for x
   x = 615,599.27/1,042.72
6. Step 6: Final answer
   x = 590.38