Finding the Fourth Proportional to 2,113.96, 3,171.30 and 815.32

Step by Step Solution

1. Step 1: Write the proportion equation
   2,113.96 : 3,171.30 = 815.32 : x
2. Step 2: Convert to fraction form
   2,113.96/3,171.30 = 815.32/x
3. Step 3: Cross multiply
   2,113.96x = 3,171.30 × 815.32
4. Step 4: Simplify right side
   2,113.96x = 2,585,624.32
5. Step 5: Solve for x
   x = 2,585,624.32/2,113.96
6. Step 6: Final answer
   x = 1,223.12