Finding the Fourth Proportional to 1,016.84, 1,394.89 and 989.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,016.84 : 1,394.89 = 989.80 : x
2. Step 2: Convert to fraction form
   1,016.84/1,394.89 = 989.80/x
3. Step 3: Cross multiply
   1,016.84x = 1,394.89 × 989.80
4. Step 4: Simplify right side
   1,016.84x = 1,380,662.12
5. Step 5: Solve for x
   x = 1,380,662.12/1,016.84
6. Step 6: Final answer
   x = 1,357.80