Finding the Fourth Proportional to 5,256.96, 7,870.72 and 2,786.20

Step by Step Solution

1. Step 1: Write the proportion equation
   5,256.96 : 7,870.72 = 2,786.20 : x
2. Step 2: Convert to fraction form
   5,256.96/7,870.72 = 2,786.20/x
3. Step 3: Cross multiply
   5,256.96x = 7,870.72 × 2,786.20
4. Step 4: Simplify right side
   5,256.96x = 21,929,400.06
5. Step 5: Solve for x
   x = 21,929,400.06/5,256.96
6. Step 6: Final answer
   x = 4,171.50