Finding the Fourth Proportional to 1,391.56, 1,918.40 and 1,036.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.56 : 1,918.40 = 1,036.78 : x
2. Step 2: Convert to fraction form
   1,391.56/1,918.40 = 1,036.78/x
3. Step 3: Cross multiply
   1,391.56x = 1,918.40 × 1,036.78
4. Step 4: Simplify right side
   1,391.56x = 1,988,958.75
5. Step 5: Solve for x
   x = 1,988,958.75/1,391.56
6. Step 6: Final answer
   x = 1,429.30