Finding the Third Proportional to 90,400 and 138,288

Step by Step Solution

1. Step 1: Write the proportion equation
   90,400 : 138,288 = 138,288 : x
2. Step 2: Convert to fraction form
   90,400/138,288 = 138,288/x
3. Step 3: Cross multiply
   90,400x = 138,288 × 138,288
4. Step 4: Simplify right side
   90,400x = 19,123,570,944
5. Step 5: Solve for x
   x = 19,123,570,944/90,400
6. Step 6: Final answer
   x = 211,543.93