Finding the Fourth Proportional to 2,639.72, 3,644.52 and 1,645.40

Step by Step Solution

1. Step 1: Write the proportion equation
   2,639.72 : 3,644.52 = 1,645.40 : x
2. Step 2: Convert to fraction form
   2,639.72/3,644.52 = 1,645.40/x
3. Step 3: Cross multiply
   2,639.72x = 3,644.52 × 1,645.40
4. Step 4: Simplify right side
   2,639.72x = 5,996,693.21
5. Step 5: Solve for x
   x = 5,996,693.21/2,639.72
6. Step 6: Final answer
   x = 2,271.72