Finding the Fourth Proportional to 1,720.17, 2,579.72 and 1,638.09

Step by Step Solution

1. Step 1: Write the proportion equation
   1,720.17 : 2,579.72 = 1,638.09 : x
2. Step 2: Convert to fraction form
   1,720.17/2,579.72 = 1,638.09/x
3. Step 3: Cross multiply
   1,720.17x = 2,579.72 × 1,638.09
4. Step 4: Simplify right side
   1,720.17x = 4,225,805.34
5. Step 5: Solve for x
   x = 4,225,805.34/1,720.17
6. Step 6: Final answer
   x = 2,456.62