Finding the Fourth Proportional to 2,189.40, 3,285.78 and 891.96

Step by Step Solution

1. Step 1: Write the proportion equation
   2,189.40 : 3,285.78 = 891.96 : x
2. Step 2: Convert to fraction form
   2,189.40/3,285.78 = 891.96/x
3. Step 3: Cross multiply
   2,189.40x = 3,285.78 × 891.96
4. Step 4: Simplify right side
   2,189.40x = 2,930,784.33
5. Step 5: Solve for x
   x = 2,930,784.33/2,189.40
6. Step 6: Final answer
   x = 1,338.62