Finding the Fourth Proportional to 1,678.89, 2,515.59 and 856.02

Step by Step Solution

1. Step 1: Write the proportion equation
   1,678.89 : 2,515.59 = 856.02 : x
2. Step 2: Convert to fraction form
   1,678.89/2,515.59 = 856.02/x
3. Step 3: Cross multiply
   1,678.89x = 2,515.59 × 856.02
4. Step 4: Simplify right side
   1,678.89x = 2,153,395.35
5. Step 5: Solve for x
   x = 2,153,395.35/1,678.89
6. Step 6: Final answer
   x = 1,282.63