Finding the Fourth Proportional to 1,142.72, 1,576.94 and 645.52

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.72 : 1,576.94 = 645.52 : x
2. Step 2: Convert to fraction form
   1,142.72/1,576.94 = 645.52/x
3. Step 3: Cross multiply
   1,142.72x = 1,576.94 × 645.52
4. Step 4: Simplify right side
   1,142.72x = 1,017,941.56
5. Step 5: Solve for x
   x = 1,017,941.56/1,142.72
6. Step 6: Final answer
   x = 890.81