Finding the Fourth Proportional to 1,380.69, 2,071.38 and 406.79

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.69 : 2,071.38 = 406.79 : x
2. Step 2: Convert to fraction form
   1,380.69/2,071.38 = 406.79/x
3. Step 3: Cross multiply
   1,380.69x = 2,071.38 × 406.79
4. Step 4: Simplify right side
   1,380.69x = 842,606.31
5. Step 5: Solve for x
   x = 842,606.31/1,380.69
6. Step 6: Final answer
   x = 610.28