Finding the Fourth Proportional to 1,188.15, 1,639.89 and 1,089.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,188.15 : 1,639.89 = 1,089.78 : x
2. Step 2: Convert to fraction form
   1,188.15/1,639.89 = 1,089.78/x
3. Step 3: Cross multiply
   1,188.15x = 1,639.89 × 1,089.78
4. Step 4: Simplify right side
   1,188.15x = 1,787,119.32
5. Step 5: Solve for x
   x = 1,787,119.32/1,188.15
6. Step 6: Final answer
   x = 1,504.12