Finding the Third Proportional to 400.78 and 535.78

Step by Step Solution

1. Step 1: Write the proportion equation
   400.78 : 535.78 = 535.78 : x
2. Step 2: Convert to fraction form
   400.78/535.78 = 535.78/x
3. Step 3: Cross multiply
   400.78x = 535.78 × 535.78
4. Step 4: Simplify right side
   400.78x = 287,061.55
5. Step 5: Solve for x
   x = 287,061.55/400.78
6. Step 6: Final answer
   x = 716.25