Finding the Fourth Proportional to 1,055.52, 1,581.53 and 643.41

Step by Step Solution

1. Step 1: Write the proportion equation
   1,055.52 : 1,581.53 = 643.41 : x
2. Step 2: Convert to fraction form
   1,055.52/1,581.53 = 643.41/x
3. Step 3: Cross multiply
   1,055.52x = 1,581.53 × 643.41
4. Step 4: Simplify right side
   1,055.52x = 1,017,572.22
5. Step 5: Solve for x
   x = 1,017,572.22/1,055.52
6. Step 6: Final answer
   x = 964.05