Finding the Third Proportional to 261,915 and 405,696.75

Step by Step Solution

1. Step 1: Write the proportion equation
   261,915 : 405,696.75 = 405,696.75 : x
2. Step 2: Convert to fraction form
   261,915/405,696.75 = 405,696.75/x
3. Step 3: Cross multiply
   261,915x = 405,696.75 × 405,696.75
4. Step 4: Simplify right side
   261,915x = 164,589,852,960.56
5. Step 5: Solve for x
   x = 164,589,852,960.56/261,915
6. Step 6: Final answer
   x = 628,409.42