Finding the Fourth Proportional to 1,081.30, 1,619.90 and 641.62

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.30 : 1,619.90 = 641.62 : x
2. Step 2: Convert to fraction form
   1,081.30/1,619.90 = 641.62/x
3. Step 3: Cross multiply
   1,081.30x = 1,619.90 × 641.62
4. Step 4: Simplify right side
   1,081.30x = 1,039,356.02
5. Step 5: Solve for x
   x = 1,039,356.02/1,081.30
6. Step 6: Final answer
   x = 961.21