Finding the Fourth Proportional to 1,142.83, 1,577.20 and 645.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.83 : 1,577.20 = 645.57 : x
2. Step 2: Convert to fraction form
   1,142.83/1,577.20 = 645.57/x
3. Step 3: Cross multiply
   1,142.83x = 1,577.20 × 645.57
4. Step 4: Simplify right side
   1,142.83x = 1,018,193.00
5. Step 5: Solve for x
   x = 1,018,193.00/1,142.83
6. Step 6: Final answer
   x = 890.94