Finding the Third Proportional to 2,178 and 5,142

Step by Step Solution

1. Step 1: Write the proportion equation
   2,178 : 5,142 = 5,142 : x
2. Step 2: Convert to fraction form
   2,178/5,142 = 5,142/x
3. Step 3: Cross multiply
   2,178x = 5,142 × 5,142
4. Step 4: Simplify right side
   2,178x = 26,440,164
5. Step 5: Solve for x
   x = 26,440,164/2,178
6. Step 6: Final answer
   x = 12,139.65