Finding the Fourth Proportional to 1,987.12, 2,978.52 and 831.52

Step by Step Solution

1. Step 1: Write the proportion equation
   1,987.12 : 2,978.52 = 831.52 : x
2. Step 2: Convert to fraction form
   1,987.12/2,978.52 = 831.52/x
3. Step 3: Cross multiply
   1,987.12x = 2,978.52 × 831.52
4. Step 4: Simplify right side
   1,987.12x = 2,476,698.95
5. Step 5: Solve for x
   x = 2,476,698.95/1,987.12
6. Step 6: Final answer
   x = 1,246.38