Finding the Fourth Proportional to 1,290.48, 1,780.88 and 766.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,290.48 : 1,780.88 = 766.72 : x
2. Step 2: Convert to fraction form
   1,290.48/1,780.88 = 766.72/x
3. Step 3: Cross multiply
   1,290.48x = 1,780.88 × 766.72
4. Step 4: Simplify right side
   1,290.48x = 1,365,436.31
5. Step 5: Solve for x
   x = 1,365,436.31/1,290.48
6. Step 6: Final answer
   x = 1,058.08