Finding the Fourth Proportional to 1,986.10, 2,980.49 and 816.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,986.10 : 2,980.49 = 816.31 : x
2. Step 2: Convert to fraction form
   1,986.10/2,980.49 = 816.31/x
3. Step 3: Cross multiply
   1,986.10x = 2,980.49 × 816.31
4. Step 4: Simplify right side
   1,986.10x = 2,433,003.79
5. Step 5: Solve for x
   x = 2,433,003.79/1,986.10
6. Step 6: Final answer
   x = 1,225.02