Finding the Third Proportional to 139,879.50 and 210,990

Step by Step Solution

1. Step 1: Write the proportion equation
   139,879.50 : 210,990 = 210,990 : x
2. Step 2: Convert to fraction form
   139,879.50/210,990 = 210,990/x
3. Step 3: Cross multiply
   139,879.50x = 210,990 × 210,990
4. Step 4: Simplify right side
   139,879.50x = 44,516,780,100
5. Step 5: Solve for x
   x = 44,516,780,100/139,879.50
6. Step 6: Final answer
   x = 318,250.92