Finding the Fourth Proportional to 1,142.09, 1,576.17 and 644.70

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.09 : 1,576.17 = 644.70 : x
2. Step 2: Convert to fraction form
   1,142.09/1,576.17 = 644.70/x
3. Step 3: Cross multiply
   1,142.09x = 1,576.17 × 644.70
4. Step 4: Simplify right side
   1,142.09x = 1,016,156.80
5. Step 5: Solve for x
   x = 1,016,156.80/1,142.09
6. Step 6: Final answer
   x = 889.73