Finding the Fourth Proportional to 1,145.77, 1,581.54 and 815.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,145.77 : 1,581.54 = 815.15 : x
2. Step 2: Convert to fraction form
   1,145.77/1,581.54 = 815.15/x
3. Step 3: Cross multiply
   1,145.77x = 1,581.54 × 815.15
4. Step 4: Simplify right side
   1,145.77x = 1,289,192.33
5. Step 5: Solve for x
   x = 1,289,192.33/1,145.77
6. Step 6: Final answer
   x = 1,125.18