Finding the Fourth Proportional to 1,380.31, 2,071.23 and 1,072.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.31 : 2,071.23 = 1,072.78 : x
2. Step 2: Convert to fraction form
   1,380.31/2,071.23 = 1,072.78/x
3. Step 3: Cross multiply
   1,380.31x = 2,071.23 × 1,072.78
4. Step 4: Simplify right side
   1,380.31x = 2,221,963.76
5. Step 5: Solve for x
   x = 2,221,963.76/1,380.31
6. Step 6: Final answer
   x = 1,609.76