Finding the Fourth Proportional to 978.51, 1,466.20 and 686.50

Step by Step Solution

1. Step 1: Write the proportion equation
   978.51 : 1,466.20 = 686.50 : x
2. Step 2: Convert to fraction form
   978.51/1,466.20 = 686.50/x
3. Step 3: Cross multiply
   978.51x = 1,466.20 × 686.50
4. Step 4: Simplify right side
   978.51x = 1,006,546.30
5. Step 5: Solve for x
   x = 1,006,546.30/978.51
6. Step 6: Final answer
   x = 1,028.65