Finding the Fourth Proportional to 2,111.20, 3,167.70 and 1,331.80

Step by Step Solution

1. Step 1: Write the proportion equation
   2,111.20 : 3,167.70 = 1,331.80 : x
2. Step 2: Convert to fraction form
   2,111.20/3,167.70 = 1,331.80/x
3. Step 3: Cross multiply
   2,111.20x = 3,167.70 × 1,331.80
4. Step 4: Simplify right side
   2,111.20x = 4,218,742.86
5. Step 5: Solve for x
   x = 4,218,742.86/2,111.20
6. Step 6: Final answer
   x = 1,998.27