Finding the Fourth Proportional to 1,142.87, 1,576.77 and 645.32

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.87 : 1,576.77 = 645.32 : x
2. Step 2: Convert to fraction form
   1,142.87/1,576.77 = 645.32/x
3. Step 3: Cross multiply
   1,142.87x = 1,576.77 × 645.32
4. Step 4: Simplify right side
   1,142.87x = 1,017,513.33
5. Step 5: Solve for x
   x = 1,017,513.33/1,142.87
6. Step 6: Final answer
   x = 890.32