Finding the Fourth Proportional to 2,128.02, 3,190.17 and 830.40

Step by Step Solution

1. Step 1: Write the proportion equation
   2,128.02 : 3,190.17 = 830.40 : x
2. Step 2: Convert to fraction form
   2,128.02/3,190.17 = 830.40/x
3. Step 3: Cross multiply
   2,128.02x = 3,190.17 × 830.40
4. Step 4: Simplify right side
   2,128.02x = 2,649,117.17
5. Step 5: Solve for x
   x = 2,649,117.17/2,128.02
6. Step 6: Final answer
   x = 1,244.87