Finding the Fourth Proportional to 2,099.61, 3,149.52 and 638.79

Step by Step Solution

1. Step 1: Write the proportion equation
   2,099.61 : 3,149.52 = 638.79 : x
2. Step 2: Convert to fraction form
   2,099.61/3,149.52 = 638.79/x
3. Step 3: Cross multiply
   2,099.61x = 3,149.52 × 638.79
4. Step 4: Simplify right side
   2,099.61x = 2,011,881.88
5. Step 5: Solve for x
   x = 2,011,881.88/2,099.61
6. Step 6: Final answer
   x = 958.22