Finding the Fourth Proportional to 1,921.80, 2,880.36 and 1,272.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,921.80 : 2,880.36 = 1,272.72 : x
2. Step 2: Convert to fraction form
   1,921.80/2,880.36 = 1,272.72/x
3. Step 3: Cross multiply
   1,921.80x = 2,880.36 × 1,272.72
4. Step 4: Simplify right side
   1,921.80x = 3,665,891.78
5. Step 5: Solve for x
   x = 3,665,891.78/1,921.80
6. Step 6: Final answer
   x = 1,907.53