Finding the Fourth Proportional to 2,587.50, 3,881.25 and 639.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,587.50 : 3,881.25 = 639.72 : x
2. Step 2: Convert to fraction form
   2,587.50/3,881.25 = 639.72/x
3. Step 3: Cross multiply
   2,587.50x = 3,881.25 × 639.72
4. Step 4: Simplify right side
   2,587.50x = 2,482,913.25
5. Step 5: Solve for x
   x = 2,482,913.25/2,587.50
6. Step 6: Final answer
   x = 959.58