Finding the Fourth Proportional to 1,105.31, 1,525.41 and 639.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,105.31 : 1,525.41 = 639.56 : x
2. Step 2: Convert to fraction form
   1,105.31/1,525.41 = 639.56/x
3. Step 3: Cross multiply
   1,105.31x = 1,525.41 × 639.56
4. Step 4: Simplify right side
   1,105.31x = 975,592.63
5. Step 5: Solve for x
   x = 975,592.63/1,105.31
6. Step 6: Final answer
   x = 882.64