Finding the Fourth Proportional to 1,380.17, 2,071.62 and 1,123.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.17 : 2,071.62 = 1,123.20 : x
2. Step 2: Convert to fraction form
   1,380.17/2,071.62 = 1,123.20/x
3. Step 3: Cross multiply
   1,380.17x = 2,071.62 × 1,123.20
4. Step 4: Simplify right side
   1,380.17x = 2,326,843.58
5. Step 5: Solve for x
   x = 2,326,843.58/1,380.17
6. Step 6: Final answer
   x = 1,685.91