Finding the Fourth Proportional to 1,142.47, 1,576.56 and 645.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.47 : 1,576.56 = 645.10 : x
2. Step 2: Convert to fraction form
   1,142.47/1,576.56 = 645.10/x
3. Step 3: Cross multiply
   1,142.47x = 1,576.56 × 645.10
4. Step 4: Simplify right side
   1,142.47x = 1,017,030.97
5. Step 5: Solve for x
   x = 1,017,030.97/1,142.47
6. Step 6: Final answer
   x = 890.21