Finding the Fourth Proportional to 1,007.85, 1,390.72 and 588.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.85 : 1,390.72 = 588.15 : x
2. Step 2: Convert to fraction form
   1,007.85/1,390.72 = 588.15/x
3. Step 3: Cross multiply
   1,007.85x = 1,390.72 × 588.15
4. Step 4: Simplify right side
   1,007.85x = 817,951.97
5. Step 5: Solve for x
   x = 817,951.97/1,007.85
6. Step 6: Final answer
   x = 811.58