Finding the Fourth Proportional to 2,921.12, 4,380.72 and 972.80

Step by Step Solution

1. Step 1: Write the proportion equation
   2,921.12 : 4,380.72 = 972.80 : x
2. Step 2: Convert to fraction form
   2,921.12/4,380.72 = 972.80/x
3. Step 3: Cross multiply
   2,921.12x = 4,380.72 × 972.80
4. Step 4: Simplify right side
   2,921.12x = 4,261,564.42
5. Step 5: Solve for x
   x = 4,261,564.42/2,921.12
6. Step 6: Final answer
   x = 1,458.88