Finding the Third Proportional to 9,840 and 21,139

Step by Step Solution

1. Step 1: Write the proportion equation
   9,840 : 21,139 = 21,139 : x
2. Step 2: Convert to fraction form
   9,840/21,139 = 21,139/x
3. Step 3: Cross multiply
   9,840x = 21,139 × 21,139
4. Step 4: Simplify right side
   9,840x = 446,857,321
5. Step 5: Solve for x
   x = 446,857,321/9,840
6. Step 6: Final answer
   x = 45,412.33