Finding the Fourth Proportional to 1,584.78, 2,187.04 and 921.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,584.78 : 2,187.04 = 921.72 : x
2. Step 2: Convert to fraction form
   1,584.78/2,187.04 = 921.72/x
3. Step 3: Cross multiply
   1,584.78x = 2,187.04 × 921.72
4. Step 4: Simplify right side
   1,584.78x = 2,015,838.51
5. Step 5: Solve for x
   x = 2,015,838.51/1,584.78
6. Step 6: Final answer
   x = 1,272.00