Finding the Fourth Proportional to 1,111.15, 1,533.04 and 638.87

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.15 : 1,533.04 = 638.87 : x
2. Step 2: Convert to fraction form
   1,111.15/1,533.04 = 638.87/x
3. Step 3: Cross multiply
   1,111.15x = 1,533.04 × 638.87
4. Step 4: Simplify right side
   1,111.15x = 979,415.50
5. Step 5: Solve for x
   x = 979,415.50/1,111.15
6. Step 6: Final answer
   x = 881.44