Finding the Third Proportional to 242.50 and 394.50

Step by Step Solution

1. Step 1: Write the proportion equation
   242.50 : 394.50 = 394.50 : x
2. Step 2: Convert to fraction form
   242.50/394.50 = 394.50/x
3. Step 3: Cross multiply
   242.50x = 394.50 × 394.50
4. Step 4: Simplify right side
   242.50x = 155,630.25
5. Step 5: Solve for x
   x = 155,630.25/242.50
6. Step 6: Final answer
   x = 641.77