Finding the Fourth Proportional to 1,055.05, 1,580.49 and 643.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,055.05 : 1,580.49 = 643.15 : x
2. Step 2: Convert to fraction form
   1,055.05/1,580.49 = 643.15/x
3. Step 3: Cross multiply
   1,055.05x = 1,580.49 × 643.15
4. Step 4: Simplify right side
   1,055.05x = 1,016,492.14
5. Step 5: Solve for x
   x = 1,016,492.14/1,055.05
6. Step 6: Final answer
   x = 963.45