Finding the Fourth Proportional to 1,152.68, 1,590.72 and 687.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,152.68 : 1,590.72 = 687.20 : x
2. Step 2: Convert to fraction form
   1,152.68/1,590.72 = 687.20/x
3. Step 3: Cross multiply
   1,152.68x = 1,590.72 × 687.20
4. Step 4: Simplify right side
   1,152.68x = 1,093,142.78
5. Step 5: Solve for x
   x = 1,093,142.78/1,152.68
6. Step 6: Final answer
   x = 948.35