Finding the Fourth Proportional to 2,188.78, 3,283.78 and 1,215.57

Step by Step Solution

1. Step 1: Write the proportion equation
   2,188.78 : 3,283.78 = 1,215.57 : x
2. Step 2: Convert to fraction form
   2,188.78/3,283.78 = 1,215.57/x
3. Step 3: Cross multiply
   2,188.78x = 3,283.78 × 1,215.57
4. Step 4: Simplify right side
   2,188.78x = 3,991,659.28
5. Step 5: Solve for x
   x = 3,991,659.28/2,188.78
6. Step 6: Final answer
   x = 1,823.69