Finding the Fourth Proportional to 1,815.57, 2,505.47 and 987.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,815.57 : 2,505.47 = 987.57 : x
2. Step 2: Convert to fraction form
   1,815.57/2,505.47 = 987.57/x
3. Step 3: Cross multiply
   1,815.57x = 2,505.47 × 987.57
4. Step 4: Simplify right side
   1,815.57x = 2,474,327.01
5. Step 5: Solve for x
   x = 2,474,327.01/1,815.57
6. Step 6: Final answer
   x = 1,362.84