Finding the Third Proportional to 42,990 and 65,720

Step by Step Solution

1. Step 1: Write the proportion equation
   42,990 : 65,720 = 65,720 : x
2. Step 2: Convert to fraction form
   42,990/65,720 = 65,720/x
3. Step 3: Cross multiply
   42,990x = 65,720 × 65,720
4. Step 4: Simplify right side
   42,990x = 4,319,118,400
5. Step 5: Solve for x
   x = 4,319,118,400/42,990
6. Step 6: Final answer
   x = 100,467.98