Finding the Third Proportional to 478.78 and 853.78

Step by Step Solution

1. Step 1: Write the proportion equation
   478.78 : 853.78 = 853.78 : x
2. Step 2: Convert to fraction form
   478.78/853.78 = 853.78/x
3. Step 3: Cross multiply
   478.78x = 853.78 × 853.78
4. Step 4: Simplify right side
   478.78x = 728,942.42
5. Step 5: Solve for x
   x = 728,942.42/478.78
6. Step 6: Final answer
   x = 1,522.50