Finding the Third Proportional to 221.50 and 578.50

Step by Step Solution

1. Step 1: Write the proportion equation
   221.50 : 578.50 = 578.50 : x
2. Step 2: Convert to fraction form
   221.50/578.50 = 578.50/x
3. Step 3: Cross multiply
   221.50x = 578.50 × 578.50
4. Step 4: Simplify right side
   221.50x = 334,662.25
5. Step 5: Solve for x
   x = 334,662.25/221.50
6. Step 6: Final answer
   x = 1,510.89