Finding the Fourth Proportional to 1,431.20, 1,982.72 and 1,397.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,431.20 : 1,982.72 = 1,397.18 : x
2. Step 2: Convert to fraction form
   1,431.20/1,982.72 = 1,397.18/x
3. Step 3: Cross multiply
   1,431.20x = 1,982.72 × 1,397.18
4. Step 4: Simplify right side
   1,431.20x = 2,770,199.83
5. Step 5: Solve for x
   x = 2,770,199.83/1,431.20
6. Step 6: Final answer
   x = 1,935.59