Finding the Fourth Proportional to 1,380.72, 2,070.84 and 406.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.72 : 2,070.84 = 406.72 : x
2. Step 2: Convert to fraction form
   1,380.72/2,070.84 = 406.72/x
3. Step 3: Cross multiply
   1,380.72x = 2,070.84 × 406.72
4. Step 4: Simplify right side
   1,380.72x = 842,252.04
5. Step 5: Solve for x
   x = 842,252.04/1,380.72
6. Step 6: Final answer
   x = 610.01