Finding the Fourth Proportional to 1,143.19, 1,577.83 and 645.83

Step by Step Solution

1. Step 1: Write the proportion equation
   1,143.19 : 1,577.83 = 645.83 : x
2. Step 2: Convert to fraction form
   1,143.19/1,577.83 = 645.83/x
3. Step 3: Cross multiply
   1,143.19x = 1,577.83 × 645.83
4. Step 4: Simplify right side
   1,143.19x = 1,019,012.28
5. Step 5: Solve for x
   x = 1,019,012.28/1,143.19
6. Step 6: Final answer
   x = 891.38