Finding the Fourth Proportional to 1,320.74, 1,980.72 and 443.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,320.74 : 1,980.72 = 443.10 : x
2. Step 2: Convert to fraction form
   1,320.74/1,980.72 = 443.10/x
3. Step 3: Cross multiply
   1,320.74x = 1,980.72 × 443.10
4. Step 4: Simplify right side
   1,320.74x = 877,645.88
5. Step 5: Solve for x
   x = 877,645.88/1,320.74
6. Step 6: Final answer
   x = 664.51