Finding the Third Proportional to 78,621.50 and 172,688

Step by Step Solution

1. Step 1: Write the proportion equation
   78,621.50 : 172,688 = 172,688 : x
2. Step 2: Convert to fraction form
   78,621.50/172,688 = 172,688/x
3. Step 3: Cross multiply
   78,621.50x = 172,688 × 172,688
4. Step 4: Simplify right side
   78,621.50x = 29,821,145,344
5. Step 5: Solve for x
   x = 29,821,145,344/78,621.50
6. Step 6: Final answer
   x = 379,300.13