Finding the Fourth Proportional to 1,111.83, 1,533.83 and 639.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.83 : 1,533.83 = 639.61 : x
2. Step 2: Convert to fraction form
   1,111.83/1,533.83 = 639.61/x
3. Step 3: Cross multiply
   1,111.83x = 1,533.83 × 639.61
4. Step 4: Simplify right side
   1,111.83x = 981,053.01
5. Step 5: Solve for x
   x = 981,053.01/1,111.83
6. Step 6: Final answer
   x = 882.38