Finding the Fourth Proportional to 2,143.97, 3,215.90 and 989.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,143.97 : 3,215.90 = 989.72 : x
2. Step 2: Convert to fraction form
   2,143.97/3,215.90 = 989.72/x
3. Step 3: Cross multiply
   2,143.97x = 3,215.90 × 989.72
4. Step 4: Simplify right side
   2,143.97x = 3,182,840.55
5. Step 5: Solve for x
   x = 3,182,840.55/2,143.97
6. Step 6: Final answer
   x = 1,484.55