Finding the Third Proportional to 242.58 and 402.89

Step by Step Solution

1. Step 1: Write the proportion equation
   242.58 : 402.89 = 402.89 : x
2. Step 2: Convert to fraction form
   242.58/402.89 = 402.89/x
3. Step 3: Cross multiply
   242.58x = 402.89 × 402.89
4. Step 4: Simplify right side
   242.58x = 162,320.86
5. Step 5: Solve for x
   x = 162,320.86/242.58
6. Step 6: Final answer
   x = 669.15