Finding the Fourth Proportional to 1,288.32, 1,777.30 and 790.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.32 : 1,777.30 = 790.78 : x
2. Step 2: Convert to fraction form
   1,288.32/1,777.30 = 790.78/x
3. Step 3: Cross multiply
   1,288.32x = 1,777.30 × 790.78
4. Step 4: Simplify right side
   1,288.32x = 1,405,453.29
5. Step 5: Solve for x
   x = 1,405,453.29/1,288.32
6. Step 6: Final answer
   x = 1,090.92