Finding the Fourth Proportional to 1,143.09, 1,577.59 and 645.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,143.09 : 1,577.59 = 645.89 : x
2. Step 2: Convert to fraction form
   1,143.09/1,577.59 = 645.89/x
3. Step 3: Cross multiply
   1,143.09x = 1,577.59 × 645.89
4. Step 4: Simplify right side
   1,143.09x = 1,018,940.10
5. Step 5: Solve for x
   x = 1,018,940.10/1,143.09
6. Step 6: Final answer
   x = 891.39