Finding the Third Proportional to 648.84 and 1,421.72

Step by Step Solution

1. Step 1: Write the proportion equation
   648.84 : 1,421.72 = 1,421.72 : x
2. Step 2: Convert to fraction form
   648.84/1,421.72 = 1,421.72/x
3. Step 3: Cross multiply
   648.84x = 1,421.72 × 1,421.72
4. Step 4: Simplify right side
   648.84x = 2,021,284.20
5. Step 5: Solve for x
   x = 2,021,284.20/648.84
6. Step 6: Final answer
   x = 3,115.21