Finding the Third Proportional to 78,391.50 and 172,390.50

Step by Step Solution

1. Step 1: Write the proportion equation
   78,391.50 : 172,390.50 = 172,390.50 : x
2. Step 2: Convert to fraction form
   78,391.50/172,390.50 = 172,390.50/x
3. Step 3: Cross multiply
   78,391.50x = 172,390.50 × 172,390.50
4. Step 4: Simplify right side
   78,391.50x = 29,718,484,490.25
5. Step 5: Solve for x
   x = 29,718,484,490.25/78,391.50
6. Step 6: Final answer
   x = 379,103.40