Finding the Third Proportional to 310.69 and 678.56

Step by Step Solution

1. Step 1: Write the proportion equation
   310.69 : 678.56 = 678.56 : x
2. Step 2: Convert to fraction form
   310.69/678.56 = 678.56/x
3. Step 3: Cross multiply
   310.69x = 678.56 × 678.56
4. Step 4: Simplify right side
   310.69x = 460,447.07
5. Step 5: Solve for x
   x = 460,447.07/310.69
6. Step 6: Final answer
   x = 1,482.03