Finding the Fourth Proportional to 1,391.82, 2,087.72 and 417.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.82 : 2,087.72 = 417.88 : x
2. Step 2: Convert to fraction form
   1,391.82/2,087.72 = 417.88/x
3. Step 3: Cross multiply
   1,391.82x = 2,087.72 × 417.88
4. Step 4: Simplify right side
   1,391.82x = 872,414.34
5. Step 5: Solve for x
   x = 872,414.34/1,391.82
6. Step 6: Final answer
   x = 626.82