Finding the Fourth Proportional to 1,080.41, 1,621.83 and 642.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.41 : 1,621.83 = 642.61 : x
2. Step 2: Convert to fraction form
   1,080.41/1,621.83 = 642.61/x
3. Step 3: Cross multiply
   1,080.41x = 1,621.83 × 642.61
4. Step 4: Simplify right side
   1,080.41x = 1,042,196.07
5. Step 5: Solve for x
   x = 1,042,196.07/1,080.41
6. Step 6: Final answer
   x = 964.63