Finding the Fourth Proportional to 1,042.72, 1,561.94 and 521.16

Step by Step Solution

1. Step 1: Write the proportion equation
   1,042.72 : 1,561.94 = 521.16 : x
2. Step 2: Convert to fraction form
   1,042.72/1,561.94 = 521.16/x
3. Step 3: Cross multiply
   1,042.72x = 1,561.94 × 521.16
4. Step 4: Simplify right side
   1,042.72x = 814,020.65
5. Step 5: Solve for x
   x = 814,020.65/1,042.72
6. Step 6: Final answer
   x = 780.67