Finding the Third Proportional to 399.75 and 772.50

Step by Step Solution

1. Step 1: Write the proportion equation
   399.75 : 772.50 = 772.50 : x
2. Step 2: Convert to fraction form
   399.75/772.50 = 772.50/x
3. Step 3: Cross multiply
   399.75x = 772.50 × 772.50
4. Step 4: Simplify right side
   399.75x = 596,756.25
5. Step 5: Solve for x
   x = 596,756.25/399.75
6. Step 6: Final answer
   x = 1,492.82