Finding the Fourth Proportional to 1,142.48, 1,576.58 and 645.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.48 : 1,576.58 = 645.10 : x
2. Step 2: Convert to fraction form
   1,142.48/1,576.58 = 645.10/x
3. Step 3: Cross multiply
   1,142.48x = 1,576.58 × 645.10
4. Step 4: Simplify right side
   1,142.48x = 1,017,051.76
5. Step 5: Solve for x
   x = 1,017,051.76/1,142.48
6. Step 6: Final answer
   x = 890.21