Finding the Fourth Proportional to 2,191.20, 3,280.56 and 1,213.68

Step by Step Solution

1. Step 1: Write the proportion equation
   2,191.20 : 3,280.56 = 1,213.68 : x
2. Step 2: Convert to fraction form
   2,191.20/3,280.56 = 1,213.68/x
3. Step 3: Cross multiply
   2,191.20x = 3,280.56 × 1,213.68
4. Step 4: Simplify right side
   2,191.20x = 3,981,550.06
5. Step 5: Solve for x
   x = 3,981,550.06/2,191.20
6. Step 6: Final answer
   x = 1,817.06