Finding the Fourth Proportional to 1,111.25, 1,533.56 and 639.27

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.25 : 1,533.56 = 639.27 : x
2. Step 2: Convert to fraction form
   1,111.25/1,533.56 = 639.27/x
3. Step 3: Cross multiply
   1,111.25x = 1,533.56 × 639.27
4. Step 4: Simplify right side
   1,111.25x = 980,355.70
5. Step 5: Solve for x
   x = 980,355.70/1,111.25
6. Step 6: Final answer
   x = 882.21