Finding the Fourth Proportional to 2,112.71, 2,915.55 and 1,228.55

Step by Step Solution

1. Step 1: Write the proportion equation
   2,112.71 : 2,915.55 = 1,228.55 : x
2. Step 2: Convert to fraction form
   2,112.71/2,915.55 = 1,228.55/x
3. Step 3: Cross multiply
   2,112.71x = 2,915.55 × 1,228.55
4. Step 4: Simplify right side
   2,112.71x = 3,581,884.37
5. Step 5: Solve for x
   x = 3,581,884.37/2,112.71
6. Step 6: Final answer
   x = 1,695.40