Finding the Fourth Proportional to 2,099.40, 3,148.71 and 638.16

Step by Step Solution

1. Step 1: Write the proportion equation
   2,099.40 : 3,148.71 = 638.16 : x
2. Step 2: Convert to fraction form
   2,099.40/3,148.71 = 638.16/x
3. Step 3: Cross multiply
   2,099.40x = 3,148.71 × 638.16
4. Step 4: Simplify right side
   2,099.40x = 2,009,380.77
5. Step 5: Solve for x
   x = 2,009,380.77/2,099.40
6. Step 6: Final answer
   x = 957.12