Finding the Fourth Proportional to 2,807.98, 4,212.78 and 860.47

Step by Step Solution

1. Step 1: Write the proportion equation
   2,807.98 : 4,212.78 = 860.47 : x
2. Step 2: Convert to fraction form
   2,807.98/4,212.78 = 860.47/x
3. Step 3: Cross multiply
   2,807.98x = 4,212.78 × 860.47
4. Step 4: Simplify right side
   2,807.98x = 3,624,970.81
5. Step 5: Solve for x
   x = 3,624,970.81/2,807.98
6. Step 6: Final answer
   x = 1,290.95