Finding the Fourth Proportional to 1,290.48, 1,780.82 and 766.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,290.48 : 1,780.82 = 766.50 : x
2. Step 2: Convert to fraction form
   1,290.48/1,780.82 = 766.50/x
3. Step 3: Cross multiply
   1,290.48x = 1,780.82 × 766.50
4. Step 4: Simplify right side
   1,290.48x = 1,364,998.53
5. Step 5: Solve for x
   x = 1,364,998.53/1,290.48
6. Step 6: Final answer
   x = 1,057.74