Finding the Fourth Proportional to 1,087.76, 1,631.72 and 438.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,087.76 : 1,631.72 = 438.50 : x
2. Step 2: Convert to fraction form
   1,087.76/1,631.72 = 438.50/x
3. Step 3: Cross multiply
   1,087.76x = 1,631.72 × 438.50
4. Step 4: Simplify right side
   1,087.76x = 715,498.87
5. Step 5: Solve for x
   x = 715,498.87/1,087.76
6. Step 6: Final answer
   x = 657.78