Finding the Fourth Proportional to 1,315.89, 1,815.75 and 818.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,315.89 : 1,815.75 = 818.55 : x
2. Step 2: Convert to fraction form
   1,315.89/1,815.75 = 818.55/x
3. Step 3: Cross multiply
   1,315.89x = 1,815.75 × 818.55
4. Step 4: Simplify right side
   1,315.89x = 1,486,282.16
5. Step 5: Solve for x
   x = 1,486,282.16/1,315.89
6. Step 6: Final answer
   x = 1,129.49