Finding the Fourth Proportional to 1,105.25, 1,525.52 and 639.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,105.25 : 1,525.52 = 639.77 : x
2. Step 2: Convert to fraction form
   1,105.25/1,525.52 = 639.77/x
3. Step 3: Cross multiply
   1,105.25x = 1,525.52 × 639.77
4. Step 4: Simplify right side
   1,105.25x = 975,981.93
5. Step 5: Solve for x
   x = 975,981.93/1,105.25
6. Step 6: Final answer
   x = 883.04