Finding the Fourth Proportional to 1,256.16, 1,728.18 and 1,221.54

Step by Step Solution

1. Step 1: Write the proportion equation
   1,256.16 : 1,728.18 = 1,221.54 : x
2. Step 2: Convert to fraction form
   1,256.16/1,728.18 = 1,221.54/x
3. Step 3: Cross multiply
   1,256.16x = 1,728.18 × 1,221.54
4. Step 4: Simplify right side
   1,256.16x = 2,111,041.00
5. Step 5: Solve for x
   x = 2,111,041.00/1,256.16
6. Step 6: Final answer
   x = 1,680.55