Finding the Fourth Proportional to 2,139.89, 3,210.30 and 659.12

Step by Step Solution

1. Step 1: Write the proportion equation
   2,139.89 : 3,210.30 = 659.12 : x
2. Step 2: Convert to fraction form
   2,139.89/3,210.30 = 659.12/x
3. Step 3: Cross multiply
   2,139.89x = 3,210.30 × 659.12
4. Step 4: Simplify right side
   2,139.89x = 2,115,956.88
5. Step 5: Solve for x
   x = 2,115,956.88/2,139.89
6. Step 6: Final answer
   x = 988.82