Finding the Fourth Proportional to 1,678.56, 2,515.24 and 855.60

Step by Step Solution

1. Step 1: Write the proportion equation
   1,678.56 : 2,515.24 = 855.60 : x
2. Step 2: Convert to fraction form
   1,678.56/2,515.24 = 855.60/x
3. Step 3: Cross multiply
   1,678.56x = 2,515.24 × 855.60
4. Step 4: Simplify right side
   1,678.56x = 2,152,039.34
5. Step 5: Solve for x
   x = 2,152,039.34/1,678.56
6. Step 6: Final answer
   x = 1,282.07