Finding the Third Proportional to 77,120 and 123,780

Step by Step Solution

1. Step 1: Write the proportion equation
   77,120 : 123,780 = 123,780 : x
2. Step 2: Convert to fraction form
   77,120/123,780 = 123,780/x
3. Step 3: Cross multiply
   77,120x = 123,780 × 123,780
4. Step 4: Simplify right side
   77,120x = 15,321,488,400
5. Step 5: Solve for x
   x = 15,321,488,400/77,120
6. Step 6: Final answer
   x = 198,670.75