Finding the Fourth Proportional to 1,561.71, 2,343.59 and 831.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,561.71 : 2,343.59 = 831.80 : x
2. Step 2: Convert to fraction form
   1,561.71/2,343.59 = 831.80/x
3. Step 3: Cross multiply
   1,561.71x = 2,343.59 × 831.80
4. Step 4: Simplify right side
   1,561.71x = 1,949,398.16
5. Step 5: Solve for x
   x = 1,949,398.16/1,561.71
6. Step 6: Final answer
   x = 1,248.25