Finding the Third Proportional to 218.50 and 417.50

Step by Step Solution

1. Step 1: Write the proportion equation
   218.50 : 417.50 = 417.50 : x
2. Step 2: Convert to fraction form
   218.50/417.50 = 417.50/x
3. Step 3: Cross multiply
   218.50x = 417.50 × 417.50
4. Step 4: Simplify right side
   218.50x = 174,306.25
5. Step 5: Solve for x
   x = 174,306.25/218.50
6. Step 6: Final answer
   x = 797.74