Finding the Fourth Proportional to 1,288.53, 1,776.09 and 1,008.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.53 : 1,776.09 = 1,008.31 : x
2. Step 2: Convert to fraction form
   1,288.53/1,776.09 = 1,008.31/x
3. Step 3: Cross multiply
   1,288.53x = 1,776.09 × 1,008.31
4. Step 4: Simplify right side
   1,288.53x = 1,790,849.31
5. Step 5: Solve for x
   x = 1,790,849.31/1,288.53
6. Step 6: Final answer
   x = 1,389.84