Finding the Fourth Proportional to 1,142.34, 1,576.50 and 644.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.34 : 1,576.50 = 644.89 : x
2. Step 2: Convert to fraction form
   1,142.34/1,576.50 = 644.89/x
3. Step 3: Cross multiply
   1,142.34x = 1,576.50 × 644.89
4. Step 4: Simplify right side
   1,142.34x = 1,016,669.09
5. Step 5: Solve for x
   x = 1,016,669.09/1,142.34
6. Step 6: Final answer
   x = 889.99