Finding the Fourth Proportional to 1,111.36, 1,533.54 and 639.32

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.36 : 1,533.54 = 639.32 : x
2. Step 2: Convert to fraction form
   1,111.36/1,533.54 = 639.32/x
3. Step 3: Cross multiply
   1,111.36x = 1,533.54 × 639.32
4. Step 4: Simplify right side
   1,111.36x = 980,422.79
5. Step 5: Solve for x
   x = 980,422.79/1,111.36
6. Step 6: Final answer
   x = 882.18