Finding the Third Proportional to 139,171.50 and 310,216.50

Step by Step Solution

1. Step 1: Write the proportion equation
   139,171.50 : 310,216.50 = 310,216.50 : x
2. Step 2: Convert to fraction form
   139,171.50/310,216.50 = 310,216.50/x
3. Step 3: Cross multiply
   139,171.50x = 310,216.50 × 310,216.50
4. Step 4: Simplify right side
   139,171.50x = 96,234,276,872.25
5. Step 5: Solve for x
   x = 96,234,276,872.25/139,171.50
6. Step 6: Final answer
   x = 691,479.77