Finding the Third Proportional to 478.78 and 715.78

Step by Step Solution

1. Step 1: Write the proportion equation
   478.78 : 715.78 = 715.78 : x
2. Step 2: Convert to fraction form
   478.78/715.78 = 715.78/x
3. Step 3: Cross multiply
   478.78x = 715.78 × 715.78
4. Step 4: Simplify right side
   478.78x = 512,342.80
5. Step 5: Solve for x
   x = 512,342.80/478.78
6. Step 6: Final answer
   x = 1,070.10