Finding the Fourth Proportional to 2,613.40, 3,915.90 and 1,379.20

Step by Step Solution

1. Step 1: Write the proportion equation
   2,613.40 : 3,915.90 = 1,379.20 : x
2. Step 2: Convert to fraction form
   2,613.40/3,915.90 = 1,379.20/x
3. Step 3: Cross multiply
   2,613.40x = 3,915.90 × 1,379.20
4. Step 4: Simplify right side
   2,613.40x = 5,400,809.28
5. Step 5: Solve for x
   x = 5,400,809.28/2,613.40
6. Step 6: Final answer
   x = 2,066.58