Finding the Third Proportional to 299,618 and 643,300

Step by Step Solution

1. Step 1: Write the proportion equation
   299,618 : 643,300 = 643,300 : x
2. Step 2: Convert to fraction form
   299,618/643,300 = 643,300/x
3. Step 3: Cross multiply
   299,618x = 643,300 × 643,300
4. Step 4: Simplify right side
   299,618x = 413,834,890,000
5. Step 5: Solve for x
   x = 413,834,890,000/299,618
6. Step 6: Final answer
   x = 1,381,208.37