Finding the Third Proportional to 5,429,920 and 7,978,667

Step by Step Solution

1. Step 1: Write the proportion equation
   5,429,920 : 7,978,667 = 7,978,667 : x
2. Step 2: Convert to fraction form
   5,429,920/7,978,667 = 7,978,667/x
3. Step 3: Cross multiply
   5,429,920x = 7,978,667 × 7,978,667
4. Step 4: Simplify right side
   5,429,920x = 63,659,127,096,889
5. Step 5: Solve for x
   x = 63,659,127,096,889/5,429,920
6. Step 6: Final answer
   x = 11,723,768.88