Finding the Third Proportional to 15.31 and 21.69

Step by Step Solution

1. Step 1: Write the proportion equation
   15.31 : 21.69 = 21.69 : x
2. Step 2: Convert to fraction form
   15.31/21.69 = 21.69/x
3. Step 3: Cross multiply
   15.31x = 21.69 × 21.69
4. Step 4: Simplify right side
   15.31x = 470.35
5. Step 5: Solve for x
   x = 470.35/15.31
6. Step 6: Final answer
   x = 30.72