Finding the Fourth Proportional to 1,380.42, 2,069.69 and 721.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.42 : 2,069.69 = 721.89 : x
2. Step 2: Convert to fraction form
   1,380.42/2,069.69 = 721.89/x
3. Step 3: Cross multiply
   1,380.42x = 2,069.69 × 721.89
4. Step 4: Simplify right side
   1,380.42x = 1,494,084.90
5. Step 5: Solve for x
   x = 1,494,084.90/1,380.42
6. Step 6: Final answer
   x = 1,082.34