Finding the Fourth Proportional to 1,275.57, 1,760.15 and 715.86

Step by Step Solution

1. Step 1: Write the proportion equation
   1,275.57 : 1,760.15 = 715.86 : x
2. Step 2: Convert to fraction form
   1,275.57/1,760.15 = 715.86/x
3. Step 3: Cross multiply
   1,275.57x = 1,760.15 × 715.86
4. Step 4: Simplify right side
   1,275.57x = 1,260,017.40
5. Step 5: Solve for x
   x = 1,260,017.40/1,275.57
6. Step 6: Final answer
   x = 987.81