Finding the Fourth Proportional to 2,309.87, 3,187.72 and 1,315.40

Step by Step Solution

1. Step 1: Write the proportion equation
   2,309.87 : 3,187.72 = 1,315.40 : x
2. Step 2: Convert to fraction form
   2,309.87/3,187.72 = 1,315.40/x
3. Step 3: Cross multiply
   2,309.87x = 3,187.72 × 1,315.40
4. Step 4: Simplify right side
   2,309.87x = 4,193,112.59
5. Step 5: Solve for x
   x = 4,193,112.59/2,309.87
6. Step 6: Final answer
   x = 1,815.30