Finding the Third Proportional to 288.56 and 422.72

Step by Step Solution

1. Step 1: Write the proportion equation
   288.56 : 422.72 = 422.72 : x
2. Step 2: Convert to fraction form
   288.56/422.72 = 422.72/x
3. Step 3: Cross multiply
   288.56x = 422.72 × 422.72
4. Step 4: Simplify right side
   288.56x = 178,691.14
5. Step 5: Solve for x
   x = 178,691.14/288.56
6. Step 6: Final answer
   x = 619.25