Finding the Fourth Proportional to 678.72, 1,017.72 and 308.10

Step by Step Solution

1. Step 1: Write the proportion equation
   678.72 : 1,017.72 = 308.10 : x
2. Step 2: Convert to fraction form
   678.72/1,017.72 = 308.10/x
3. Step 3: Cross multiply
   678.72x = 1,017.72 × 308.10
4. Step 4: Simplify right side
   678.72x = 313,559.53
5. Step 5: Solve for x
   x = 313,559.53/678.72
6. Step 6: Final answer
   x = 461.99