Finding the Third Proportional to 78,128 and 172,192

Step by Step Solution

1. Step 1: Write the proportion equation
   78,128 : 172,192 = 172,192 : x
2. Step 2: Convert to fraction form
   78,128/172,192 = 172,192/x
3. Step 3: Cross multiply
   78,128x = 172,192 × 172,192
4. Step 4: Simplify right side
   78,128x = 29,650,084,864
5. Step 5: Solve for x
   x = 29,650,084,864/78,128
6. Step 6: Final answer
   x = 379,506.51