Finding the Fourth Proportional to 1,288.62, 1,778.55 and 764.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.62 : 1,778.55 = 764.82 : x
2. Step 2: Convert to fraction form
   1,288.62/1,778.55 = 764.82/x
3. Step 3: Cross multiply
   1,288.62x = 1,778.55 × 764.82
4. Step 4: Simplify right side
   1,288.62x = 1,360,270.61
5. Step 5: Solve for x
   x = 1,360,270.61/1,288.62
6. Step 6: Final answer
   x = 1,055.60