Finding the Fourth Proportional to 1,678.18, 2,517.69 and 856.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,678.18 : 2,517.69 = 856.43 : x
2. Step 2: Convert to fraction form
   1,678.18/2,517.69 = 856.43/x
3. Step 3: Cross multiply
   1,678.18x = 2,517.69 × 856.43
4. Step 4: Simplify right side
   1,678.18x = 2,156,225.25
5. Step 5: Solve for x
   x = 2,156,225.25/1,678.18
6. Step 6: Final answer
   x = 1,284.86