Finding the Third Proportional to 300,415 and 643,476

Step by Step Solution

1. Step 1: Write the proportion equation
   300,415 : 643,476 = 643,476 : x
2. Step 2: Convert to fraction form
   300,415/643,476 = 643,476/x
3. Step 3: Cross multiply
   300,415x = 643,476 × 643,476
4. Step 4: Simplify right side
   300,415x = 414,061,362,576
5. Step 5: Solve for x
   x = 414,061,362,576/300,415
6. Step 6: Final answer
   x = 1,378,297.90