Finding the Fourth Proportional to 1,312.89, 1,811.88 and 815.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,312.89 : 1,811.88 = 815.82 : x
2. Step 2: Convert to fraction form
   1,312.89/1,811.88 = 815.82/x
3. Step 3: Cross multiply
   1,312.89x = 1,811.88 × 815.82
4. Step 4: Simplify right side
   1,312.89x = 1,478,167.94
5. Step 5: Solve for x
   x = 1,478,167.94/1,312.89
6. Step 6: Final answer
   x = 1,125.89