Finding the Fourth Proportional to 1,111.52, 1,533.99 and 639.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.52 : 1,533.99 = 639.57 : x
2. Step 2: Convert to fraction form
   1,111.52/1,533.99 = 639.57/x
3. Step 3: Cross multiply
   1,111.52x = 1,533.99 × 639.57
4. Step 4: Simplify right side
   1,111.52x = 981,083.12
5. Step 5: Solve for x
   x = 981,083.12/1,111.52
6. Step 6: Final answer
   x = 882.65