Finding the Third Proportional to 20,420 and 42,118

Step by Step Solution

1. Step 1: Write the proportion equation
   20,420 : 42,118 = 42,118 : x
2. Step 2: Convert to fraction form
   20,420/42,118 = 42,118/x
3. Step 3: Cross multiply
   20,420x = 42,118 × 42,118
4. Step 4: Simplify right side
   20,420x = 1,773,925,924
5. Step 5: Solve for x
   x = 1,773,925,924/20,420
6. Step 6: Final answer
   x = 86,871.98