Finding the Fourth Proportional to 2,189.91, 3,021.12 and 1,392.81

Step by Step Solution

1. Step 1: Write the proportion equation
   2,189.91 : 3,021.12 = 1,392.81 : x
2. Step 2: Convert to fraction form
   2,189.91/3,021.12 = 1,392.81/x
3. Step 3: Cross multiply
   2,189.91x = 3,021.12 × 1,392.81
4. Step 4: Simplify right side
   2,189.91x = 4,207,846.15
5. Step 5: Solve for x
   x = 4,207,846.15/2,189.91
6. Step 6: Final answer
   x = 1,921.47