Finding the Fourth Proportional to 2,128.92, 3,191.46 and 1,215

Step by Step Solution

1. Step 1: Write the proportion equation
   2,128.92 : 3,191.46 = 1,215 : x
2. Step 2: Convert to fraction form
   2,128.92/3,191.46 = 1,215/x
3. Step 3: Cross multiply
   2,128.92x = 3,191.46 × 1,215
4. Step 4: Simplify right side
   2,128.92x = 3,877,623.90
5. Step 5: Solve for x
   x = 3,877,623.90/2,128.92
6. Step 6: Final answer
   x = 1,821.40