Finding the Fourth Proportional to 1,608.88, 2,220.20 and 900.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,608.88 : 2,220.20 = 900.72 : x
2. Step 2: Convert to fraction form
   1,608.88/2,220.20 = 900.72/x
3. Step 3: Cross multiply
   1,608.88x = 2,220.20 × 900.72
4. Step 4: Simplify right side
   1,608.88x = 1,999,778.54
5. Step 5: Solve for x
   x = 1,999,778.54/1,608.88
6. Step 6: Final answer
   x = 1,242.96