Finding the Fourth Proportional to 1,142.52, 1,576.72 and 645.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.52 : 1,576.72 = 645.21 : x
2. Step 2: Convert to fraction form
   1,142.52/1,576.72 = 645.21/x
3. Step 3: Cross multiply
   1,142.52x = 1,576.72 × 645.21
4. Step 4: Simplify right side
   1,142.52x = 1,017,312.69
5. Step 5: Solve for x
   x = 1,017,312.69/1,142.52
6. Step 6: Final answer
   x = 890.41