Finding the Fourth Proportional to 978.11, 1,468.56 and 857.82

Step by Step Solution

1. Step 1: Write the proportion equation
   978.11 : 1,468.56 = 857.82 : x
2. Step 2: Convert to fraction form
   978.11/1,468.56 = 857.82/x
3. Step 3: Cross multiply
   978.11x = 1,468.56 × 857.82
4. Step 4: Simplify right side
   978.11x = 1,259,768.86
5. Step 5: Solve for x
   x = 1,259,768.86/978.11
6. Step 6: Final answer
   x = 1,287.96