Finding the Fourth Proportional to 1,105.06, 1,525.12 and 639.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,105.06 : 1,525.12 = 639.31 : x
2. Step 2: Convert to fraction form
   1,105.06/1,525.12 = 639.31/x
3. Step 3: Cross multiply
   1,105.06x = 1,525.12 × 639.31
4. Step 4: Simplify right side
   1,105.06x = 975,024.47
5. Step 5: Solve for x
   x = 975,024.47/1,105.06
6. Step 6: Final answer
   x = 882.33