Finding the Fourth Proportional to 1,143.27, 1,577.71 and 645.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,143.27 : 1,577.71 = 645.91 : x
2. Step 2: Convert to fraction form
   1,143.27/1,577.71 = 645.91/x
3. Step 3: Cross multiply
   1,143.27x = 1,577.71 × 645.91
4. Step 4: Simplify right side
   1,143.27x = 1,019,047.55
5. Step 5: Solve for x
   x = 1,019,047.55/1,143.27
6. Step 6: Final answer
   x = 891.34