Finding the Fourth Proportional to 1,008.72, 1,509.82 and 521.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,008.72 : 1,509.82 = 521.10 : x
2. Step 2: Convert to fraction form
   1,008.72/1,509.82 = 521.10/x
3. Step 3: Cross multiply
   1,008.72x = 1,509.82 × 521.10
4. Step 4: Simplify right side
   1,008.72x = 786,767.20
5. Step 5: Solve for x
   x = 786,767.20/1,008.72
6. Step 6: Final answer
   x = 779.97