Finding the Third Proportional to 20,402 and 42,870

Step by Step Solution

1. Step 1: Write the proportion equation
   20,402 : 42,870 = 42,870 : x
2. Step 2: Convert to fraction form
   20,402/42,870 = 42,870/x
3. Step 3: Cross multiply
   20,402x = 42,870 × 42,870
4. Step 4: Simplify right side
   20,402x = 1,837,836,900
5. Step 5: Solve for x
   x = 1,837,836,900/20,402
6. Step 6: Final answer
   x = 90,081.21