Finding the Third Proportional to 13,780 and 19,890

Step by Step Solution

1. Step 1: Write the proportion equation
   13,780 : 19,890 = 19,890 : x
2. Step 2: Convert to fraction form
   13,780/19,890 = 19,890/x
3. Step 3: Cross multiply
   13,780x = 19,890 × 19,890
4. Step 4: Simplify right side
   13,780x = 395,612,100
5. Step 5: Solve for x
   x = 395,612,100/13,780
6. Step 6: Final answer
   x = 28,709.15