Finding the Third Proportional to 678.38 and 970.31

Step by Step Solution

1. Step 1: Write the proportion equation
   678.38 : 970.31 = 970.31 : x
2. Step 2: Convert to fraction form
   678.38/970.31 = 970.31/x
3. Step 3: Cross multiply
   678.38x = 970.31 × 970.31
4. Step 4: Simplify right side
   678.38x = 941,506.35
5. Step 5: Solve for x
   x = 941,506.35/678.38
6. Step 6: Final answer
   x = 1,387.88