Finding the Fourth Proportional to 1,055.43, 1,581.60 and 664.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,055.43 : 1,581.60 = 664.50 : x
2. Step 2: Convert to fraction form
   1,055.43/1,581.60 = 664.50/x
3. Step 3: Cross multiply
   1,055.43x = 1,581.60 × 664.50
4. Step 4: Simplify right side
   1,055.43x = 1,050,973.20
5. Step 5: Solve for x
   x = 1,050,973.20/1,055.43
6. Step 6: Final answer
   x = 995.78