Finding the Fourth Proportional to 1,099.78, 1,638.89 and 1,069.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,099.78 : 1,638.89 = 1,069.71 : x
2. Step 2: Convert to fraction form
   1,099.78/1,638.89 = 1,069.71/x
3. Step 3: Cross multiply
   1,099.78x = 1,638.89 × 1,069.71
4. Step 4: Simplify right side
   1,099.78x = 1,753,137.02
5. Step 5: Solve for x
   x = 1,753,137.02/1,099.78
6. Step 6: Final answer
   x = 1,594.08