Finding the Fourth Proportional to 2,820.31, 3,892.05 and 1,561.61

Step by Step Solution

1. Step 1: Write the proportion equation
   2,820.31 : 3,892.05 = 1,561.61 : x
2. Step 2: Convert to fraction form
   2,820.31/3,892.05 = 1,561.61/x
3. Step 3: Cross multiply
   2,820.31x = 3,892.05 × 1,561.61
4. Step 4: Simplify right side
   2,820.31x = 6,077,873.93
5. Step 5: Solve for x
   x = 6,077,873.93/2,820.31
6. Step 6: Final answer
   x = 2,155.04