Finding the Third Proportional to 64,290 and 138,978

Step by Step Solution

1. Step 1: Write the proportion equation
   64,290 : 138,978 = 138,978 : x
2. Step 2: Convert to fraction form
   64,290/138,978 = 138,978/x
3. Step 3: Cross multiply
   64,290x = 138,978 × 138,978
4. Step 4: Simplify right side
   64,290x = 19,314,884,484
5. Step 5: Solve for x
   x = 19,314,884,484/64,290
6. Step 6: Final answer
   x = 300,433.73