Finding the Fourth Proportional to 978.88, 1,464.72 and 816.64

Step by Step Solution

1. Step 1: Write the proportion equation
   978.88 : 1,464.72 = 816.64 : x
2. Step 2: Convert to fraction form
   978.88/1,464.72 = 816.64/x
3. Step 3: Cross multiply
   978.88x = 1,464.72 × 816.64
4. Step 4: Simplify right side
   978.88x = 1,196,148.94
5. Step 5: Solve for x
   x = 1,196,148.94/978.88
6. Step 6: Final answer
   x = 1,221.96