Finding the Fourth Proportional to 1,288.47, 1,776.92 and 1,089.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.47 : 1,776.92 = 1,089.72 : x
2. Step 2: Convert to fraction form
   1,288.47/1,776.92 = 1,089.72/x
3. Step 3: Cross multiply
   1,288.47x = 1,776.92 × 1,089.72
4. Step 4: Simplify right side
   1,288.47x = 1,936,343.90
5. Step 5: Solve for x
   x = 1,936,343.90/1,288.47
6. Step 6: Final answer
   x = 1,502.82