Finding the Fourth Proportional to 1,142.96, 1,577.32 and 645.62

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.96 : 1,577.32 = 645.62 : x
2. Step 2: Convert to fraction form
   1,142.96/1,577.32 = 645.62/x
3. Step 3: Cross multiply
   1,142.96x = 1,577.32 × 645.62
4. Step 4: Simplify right side
   1,142.96x = 1,018,352.34
5. Step 5: Solve for x
   x = 1,018,352.34/1,142.96
6. Step 6: Final answer
   x = 890.98