Finding the Fourth Proportional to 1,602.78, 2,400.31 and 820.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,602.78 : 2,400.31 = 820.72 : x
2. Step 2: Convert to fraction form
   1,602.78/2,400.31 = 820.72/x
3. Step 3: Cross multiply
   1,602.78x = 2,400.31 × 820.72
4. Step 4: Simplify right side
   1,602.78x = 1,969,982.42
5. Step 5: Solve for x
   x = 1,969,982.42/1,602.78
6. Step 6: Final answer
   x = 1,229.10