Finding the Third Proportional to 5,077.69 and 10,390.78

Step by Step Solution

1. Step 1: Write the proportion equation
   5,077.69 : 10,390.78 = 10,390.78 : x
2. Step 2: Convert to fraction form
   5,077.69/10,390.78 = 10,390.78/x
3. Step 3: Cross multiply
   5,077.69x = 10,390.78 × 10,390.78
4. Step 4: Simplify right side
   5,077.69x = 107,968,334.99
5. Step 5: Solve for x
   x = 107,968,334.99/5,077.69
6. Step 6: Final answer
   x = 21,263.29