Finding the Third Proportional to 64,890 and 139,680

Step by Step Solution

1. Step 1: Write the proportion equation
   64,890 : 139,680 = 139,680 : x
2. Step 2: Convert to fraction form
   64,890/139,680 = 139,680/x
3. Step 3: Cross multiply
   64,890x = 139,680 × 139,680
4. Step 4: Simplify right side
   64,890x = 19,510,502,400
5. Step 5: Solve for x
   x = 19,510,502,400/64,890
6. Step 6: Final answer
   x = 300,670.40