Finding the Fourth Proportional to 1,288.85, 1,776.63 and 790.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.85 : 1,776.63 = 790.56 : x
2. Step 2: Convert to fraction form
   1,288.85/1,776.63 = 790.56/x
3. Step 3: Cross multiply
   1,288.85x = 1,776.63 × 790.56
4. Step 4: Simplify right side
   1,288.85x = 1,404,532.61
5. Step 5: Solve for x
   x = 1,404,532.61/1,288.85
6. Step 6: Final answer
   x = 1,089.76