Finding the Third Proportional to 19,980 and 42,390

Step by Step Solution

1. Step 1: Write the proportion equation
   19,980 : 42,390 = 42,390 : x
2. Step 2: Convert to fraction form
   19,980/42,390 = 42,390/x
3. Step 3: Cross multiply
   19,980x = 42,390 × 42,390
4. Step 4: Simplify right side
   19,980x = 1,796,912,100
5. Step 5: Solve for x
   x = 1,796,912,100/19,980
6. Step 6: Final answer
   x = 89,935.54