Finding the Fourth Proportional to 1,987.47, 2,978.86 and 816.75

Step by Step Solution

1. Step 1: Write the proportion equation
   1,987.47 : 2,978.86 = 816.75 : x
2. Step 2: Convert to fraction form
   1,987.47/2,978.86 = 816.75/x
3. Step 3: Cross multiply
   1,987.47x = 2,978.86 × 816.75
4. Step 4: Simplify right side
   1,987.47x = 2,432,983.91
5. Step 5: Solve for x
   x = 2,432,983.91/1,987.47
6. Step 6: Final answer
   x = 1,224.16