Finding the Fourth Proportional to 2,870.20, 4,305.56 and 921.92

Step by Step Solution

1. Step 1: Write the proportion equation
   2,870.20 : 4,305.56 = 921.92 : x
2. Step 2: Convert to fraction form
   2,870.20/4,305.56 = 921.92/x
3. Step 3: Cross multiply
   2,870.20x = 4,305.56 × 921.92
4. Step 4: Simplify right side
   2,870.20x = 3,969,381.88
5. Step 5: Solve for x
   x = 3,969,381.88/2,870.20
6. Step 6: Final answer
   x = 1,382.96