Finding the Fourth Proportional to 1,380.42, 2,071.64 and 861.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.42 : 2,071.64 = 861.18 : x
2. Step 2: Convert to fraction form
   1,380.42/2,071.64 = 861.18/x
3. Step 3: Cross multiply
   1,380.42x = 2,071.64 × 861.18
4. Step 4: Simplify right side
   1,380.42x = 1,784,050.63
5. Step 5: Solve for x
   x = 1,784,050.63/1,380.42
6. Step 6: Final answer
   x = 1,292.40