Finding the Third Proportional to 138,405 and 206,886.75

Step by Step Solution

1. Step 1: Write the proportion equation
   138,405 : 206,886.75 = 206,886.75 : x
2. Step 2: Convert to fraction form
   138,405/206,886.75 = 206,886.75/x
3. Step 3: Cross multiply
   138,405x = 206,886.75 × 206,886.75
4. Step 4: Simplify right side
   138,405x = 42,802,127,325.56
5. Step 5: Solve for x
   x = 42,802,127,325.56/138,405
6. Step 6: Final answer
   x = 309,252.75