Finding the Fourth Proportional to 2,587.10, 3,880.59 and 639.27

Step by Step Solution

1. Step 1: Write the proportion equation
   2,587.10 : 3,880.59 = 639.27 : x
2. Step 2: Convert to fraction form
   2,587.10/3,880.59 = 639.27/x
3. Step 3: Cross multiply
   2,587.10x = 3,880.59 × 639.27
4. Step 4: Simplify right side
   2,587.10x = 2,480,744.77
5. Step 5: Solve for x
   x = 2,480,744.77/2,587.10
6. Step 6: Final answer
   x = 958.89