Finding the Fourth Proportional to 1,111.33, 1,533.15 and 639.11

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.33 : 1,533.15 = 639.11 : x
2. Step 2: Convert to fraction form
   1,111.33/1,533.15 = 639.11/x
3. Step 3: Cross multiply
   1,111.33x = 1,533.15 × 639.11
4. Step 4: Simplify right side
   1,111.33x = 979,848.30
5. Step 5: Solve for x
   x = 979,848.30/1,111.33
6. Step 6: Final answer
   x = 881.69