Finding the Fourth Proportional to 1,174.27, 1,620.49 and 643.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,174.27 : 1,620.49 = 643.15 : x
2. Step 2: Convert to fraction form
   1,174.27/1,620.49 = 643.15/x
3. Step 3: Cross multiply
   1,174.27x = 1,620.49 × 643.15
4. Step 4: Simplify right side
   1,174.27x = 1,042,216.54
5. Step 5: Solve for x
   x = 1,042,216.54/1,174.27
6. Step 6: Final answer
   x = 887.55