Finding the Fourth Proportional to 1,380.45, 2,070.72 and 406.47

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.45 : 2,070.72 = 406.47 : x
2. Step 2: Convert to fraction form
   1,380.45/2,070.72 = 406.47/x
3. Step 3: Cross multiply
   1,380.45x = 2,070.72 × 406.47
4. Step 4: Simplify right side
   1,380.45x = 841,685.56
5. Step 5: Solve for x
   x = 841,685.56/1,380.45
6. Step 6: Final answer
   x = 609.72