Finding the Third Proportional to 1,388.71 and 2,172.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.71 : 2,172.76 = 2,172.76 : x
2. Step 2: Convert to fraction form
   1,388.71/2,172.76 = 2,172.76/x
3. Step 3: Cross multiply
   1,388.71x = 2,172.76 × 2,172.76
4. Step 4: Simplify right side
   1,388.71x = 4,720,893.49
5. Step 5: Solve for x
   x = 4,720,893.49/1,388.71
6. Step 6: Final answer
   x = 3,399.49