Finding the Third Proportional to 13,990.50 and 21,120.50

Step by Step Solution

1. Step 1: Write the proportion equation
   13,990.50 : 21,120.50 = 21,120.50 : x
2. Step 2: Convert to fraction form
   13,990.50/21,120.50 = 21,120.50/x
3. Step 3: Cross multiply
   13,990.50x = 21,120.50 × 21,120.50
4. Step 4: Simplify right side
   13,990.50x = 446,075,520.25
5. Step 5: Solve for x
   x = 446,075,520.25/13,990.50
6. Step 6: Final answer
   x = 31,884.17