Finding the Third Proportional to 413.81 and 661.78

Step by Step Solution

1. Step 1: Write the proportion equation
   413.81 : 661.78 = 661.78 : x
2. Step 2: Convert to fraction form
   413.81/661.78 = 661.78/x
3. Step 3: Cross multiply
   413.81x = 661.78 × 661.78
4. Step 4: Simplify right side
   413.81x = 437,954.42
5. Step 5: Solve for x
   x = 437,954.42/413.81
6. Step 6: Final answer
   x = 1,058.34