Finding the Fourth Proportional to 3,870.30, 5,805.48 and 1,405.20

Step by Step Solution

1. Step 1: Write the proportion equation
   3,870.30 : 5,805.48 = 1,405.20 : x
2. Step 2: Convert to fraction form
   3,870.30/5,805.48 = 1,405.20/x
3. Step 3: Cross multiply
   3,870.30x = 5,805.48 × 1,405.20
4. Step 4: Simplify right side
   3,870.30x = 8,157,860.50
5. Step 5: Solve for x
   x = 8,157,860.50/3,870.30
6. Step 6: Final answer
   x = 2,107.81