Finding the Fourth Proportional to 1,105.96, 1,525.86 and 639.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,105.96 : 1,525.86 = 639.88 : x
2. Step 2: Convert to fraction form
   1,105.96/1,525.86 = 639.88/x
3. Step 3: Cross multiply
   1,105.96x = 1,525.86 × 639.88
4. Step 4: Simplify right side
   1,105.96x = 976,367.30
5. Step 5: Solve for x
   x = 976,367.30/1,105.96
6. Step 6: Final answer
   x = 882.82