Finding the Fourth Proportional to 3,913.32, 5,870.20 and 991.65

Step by Step Solution

1. Step 1: Write the proportion equation
   3,913.32 : 5,870.20 = 991.65 : x
2. Step 2: Convert to fraction form
   3,913.32/5,870.20 = 991.65/x
3. Step 3: Cross multiply
   3,913.32x = 5,870.20 × 991.65
4. Step 4: Simplify right side
   3,913.32x = 5,821,183.83
5. Step 5: Solve for x
   x = 5,821,183.83/3,913.32
6. Step 6: Final answer
   x = 1,487.53