Finding the Fourth Proportional to 661,510.99, 991,017.86 and 390,831.47

Step by Step Solution

1. Step 1: Write the proportion equation
   661,510.99 : 991,017.86 = 390,831.47 : x
2. Step 2: Convert to fraction form
   661,510.99/991,017.86 = 390,831.47/x
3. Step 3: Cross multiply
   661,510.99x = 991,017.86 × 390,831.47
4. Step 4: Simplify right side
   661,510.99x = 387,320,967,020.05
5. Step 5: Solve for x
   x = 387,320,967,020.05/661,510.99
6. Step 6: Final answer
   x = 585,509.50