Finding the Fourth Proportional to 1,380.40, 1,905.15 and 1,048.28

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.40 : 1,905.15 = 1,048.28 : x
2. Step 2: Convert to fraction form
   1,380.40/1,905.15 = 1,048.28/x
3. Step 3: Cross multiply
   1,380.40x = 1,905.15 × 1,048.28
4. Step 4: Simplify right side
   1,380.40x = 1,997,130.64
5. Step 5: Solve for x
   x = 1,997,130.64/1,380.40
6. Step 6: Final answer
   x = 1,446.78