Finding the Fourth Proportional to 1,143.05, 1,577.42 and 645.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,143.05 : 1,577.42 = 645.69 : x
2. Step 2: Convert to fraction form
   1,143.05/1,577.42 = 645.69/x
3. Step 3: Cross multiply
   1,143.05x = 1,577.42 × 645.69
4. Step 4: Simplify right side
   1,143.05x = 1,018,521.09
5. Step 5: Solve for x
   x = 1,018,521.09/1,143.05
6. Step 6: Final answer
   x = 891.06