Finding the Fourth Proportional to 3,913.36, 5,870.03 and 991.89

Step by Step Solution

1. Step 1: Write the proportion equation
   3,913.36 : 5,870.03 = 991.89 : x
2. Step 2: Convert to fraction form
   3,913.36/5,870.03 = 991.89/x
3. Step 3: Cross multiply
   3,913.36x = 5,870.03 × 991.89
4. Step 4: Simplify right side
   3,913.36x = 5,822,426.54
5. Step 5: Solve for x
   x = 5,822,426.54/3,913.36
6. Step 6: Final answer
   x = 1,487.83