Finding the Third Proportional to 242.50 and 390.38

Step by Step Solution

1. Step 1: Write the proportion equation
   242.50 : 390.38 = 390.38 : x
2. Step 2: Convert to fraction form
   242.50/390.38 = 390.38/x
3. Step 3: Cross multiply
   242.50x = 390.38 × 390.38
4. Step 4: Simplify right side
   242.50x = 152,392.64
5. Step 5: Solve for x
   x = 152,392.64/242.50
6. Step 6: Final answer
   x = 628.42