Finding the Fourth Proportional to 1,007.69, 1,381.55 and 989.19

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.69 : 1,381.55 = 989.19 : x
2. Step 2: Convert to fraction form
   1,007.69/1,381.55 = 989.19/x
3. Step 3: Cross multiply
   1,007.69x = 1,381.55 × 989.19
4. Step 4: Simplify right side
   1,007.69x = 1,366,610.50
5. Step 5: Solve for x
   x = 1,366,610.50/1,007.69
6. Step 6: Final answer
   x = 1,356.19