Finding the Fourth Proportional to 2,870.28, 4,302.63 and 921.15

Step by Step Solution

1. Step 1: Write the proportion equation
   2,870.28 : 4,302.63 = 921.15 : x
2. Step 2: Convert to fraction form
   2,870.28/4,302.63 = 921.15/x
3. Step 3: Cross multiply
   2,870.28x = 4,302.63 × 921.15
4. Step 4: Simplify right side
   2,870.28x = 3,963,367.62
5. Step 5: Solve for x
   x = 3,963,367.62/2,870.28
6. Step 6: Final answer
   x = 1,380.83