Finding the Third Proportional to 12,980 and 21,090

Step by Step Solution

1. Step 1: Write the proportion equation
   12,980 : 21,090 = 21,090 : x
2. Step 2: Convert to fraction form
   12,980/21,090 = 21,090/x
3. Step 3: Cross multiply
   12,980x = 21,090 × 21,090
4. Step 4: Simplify right side
   12,980x = 444,788,100
5. Step 5: Solve for x
   x = 444,788,100/12,980
6. Step 6: Final answer
   x = 34,267.19