Finding the Fourth Proportional to 1,142.76, 1,577.04 and 645.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.76 : 1,577.04 = 645.37 : x
2. Step 2: Convert to fraction form
   1,142.76/1,577.04 = 645.37/x
3. Step 3: Cross multiply
   1,142.76x = 1,577.04 × 645.37
4. Step 4: Simplify right side
   1,142.76x = 1,017,763.19
5. Step 5: Solve for x
   x = 1,017,763.19/1,142.76
6. Step 6: Final answer
   x = 890.62