Finding the Fourth Proportional to 1,142.42, 1,576.30 and 644.86

Step by Step Solution

1. Step 1: Write the proportion equation
   1,142.42 : 1,576.30 = 644.86 : x
2. Step 2: Convert to fraction form
   1,142.42/1,576.30 = 644.86/x
3. Step 3: Cross multiply
   1,142.42x = 1,576.30 × 644.86
4. Step 4: Simplify right side
   1,142.42x = 1,016,492.82
5. Step 5: Solve for x
   x = 1,016,492.82/1,142.42
6. Step 6: Final answer
   x = 889.77