Finding the Fourth Proportional to 1,010.72, 1,516.17 and 280.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,010.72 : 1,516.17 = 280.31 : x
2. Step 2: Convert to fraction form
   1,010.72/1,516.17 = 280.31/x
3. Step 3: Cross multiply
   1,010.72x = 1,516.17 × 280.31
4. Step 4: Simplify right side
   1,010.72x = 424,990.03
5. Step 5: Solve for x
   x = 424,990.03/1,010.72
6. Step 6: Final answer
   x = 420.48