Finding the Fourth Proportional to 1,640.39, 2,458.76 and 772.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,640.39 : 2,458.76 = 772.88 : x
2. Step 2: Convert to fraction form
   1,640.39/2,458.76 = 772.88/x
3. Step 3: Cross multiply
   1,640.39x = 2,458.76 × 772.88
4. Step 4: Simplify right side
   1,640.39x = 1,900,310.27
5. Step 5: Solve for x
   x = 1,900,310.27/1,640.39
6. Step 6: Final answer
   x = 1,158.45