Finding the Third Proportional to 5,390 and 10,978

Step by Step Solution

1. Step 1: Write the proportion equation
   5,390 : 10,978 = 10,978 : x
2. Step 2: Convert to fraction form
   5,390/10,978 = 10,978/x
3. Step 3: Cross multiply
   5,390x = 10,978 × 10,978
4. Step 4: Simplify right side
   5,390x = 120,516,484
5. Step 5: Solve for x
   x = 120,516,484/5,390
6. Step 6: Final answer
   x = 22,359.27