Finding the Fourth Proportional to 1,380.34, 2,071.54 and 861.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.34 : 2,071.54 = 861.10 : x
2. Step 2: Convert to fraction form
   1,380.34/2,071.54 = 861.10/x
3. Step 3: Cross multiply
   1,380.34x = 2,071.54 × 861.10
4. Step 4: Simplify right side
   1,380.34x = 1,783,803.09
5. Step 5: Solve for x
   x = 1,783,803.09/1,380.34
6. Step 6: Final answer
   x = 1,292.29