Finding the Third Proportional to 31,821 and 68,878.50

Step by Step Solution

1. Step 1: Write the proportion equation
   31,821 : 68,878.50 = 68,878.50 : x
2. Step 2: Convert to fraction form
   31,821/68,878.50 = 68,878.50/x
3. Step 3: Cross multiply
   31,821x = 68,878.50 × 68,878.50
4. Step 4: Simplify right side
   31,821x = 4,744,247,762.25
5. Step 5: Solve for x
   x = 4,744,247,762.25/31,821
6. Step 6: Final answer
   x = 149,091.72