Finding the Third Proportional to 215.16 and 288.56

Step by Step Solution

1. Step 1: Write the proportion equation
   215.16 : 288.56 = 288.56 : x
2. Step 2: Convert to fraction form
   215.16/288.56 = 288.56/x
3. Step 3: Cross multiply
   215.16x = 288.56 × 288.56
4. Step 4: Simplify right side
   215.16x = 83,268.32
5. Step 5: Solve for x
   x = 83,268.32/215.16
6. Step 6: Final answer
   x = 387.01