Finding the Fourth Proportional to 1,131.24, 1,560.87 and 688.35

Step by Step Solution

1. Step 1: Write the proportion equation
   1,131.24 : 1,560.87 = 688.35 : x
2. Step 2: Convert to fraction form
   1,131.24/1,560.87 = 688.35/x
3. Step 3: Cross multiply
   1,131.24x = 1,560.87 × 688.35
4. Step 4: Simplify right side
   1,131.24x = 1,074,424.86
5. Step 5: Solve for x
   x = 1,074,424.86/1,131.24
6. Step 6: Final answer
   x = 949.78