Finding the Third Proportional to 78,140 and 172,216

Step by Step Solution

1. Step 1: Write the proportion equation
   78,140 : 172,216 = 172,216 : x
2. Step 2: Convert to fraction form
   78,140/172,216 = 172,216/x
3. Step 3: Cross multiply
   78,140x = 172,216 × 172,216
4. Step 4: Simplify right side
   78,140x = 29,658,350,656
5. Step 5: Solve for x
   x = 29,658,350,656/78,140
6. Step 6: Final answer
   x = 379,554.01