Finding the Fourth Proportional to 5,178.06, 7,145.72 and 2,820.20

Step by Step Solution

1. Step 1: Write the proportion equation
   5,178.06 : 7,145.72 = 2,820.20 : x
2. Step 2: Convert to fraction form
   5,178.06/7,145.72 = 2,820.20/x
3. Step 3: Cross multiply
   5,178.06x = 7,145.72 × 2,820.20
4. Step 4: Simplify right side
   5,178.06x = 20,152,356.39
5. Step 5: Solve for x
   x = 20,152,356.39/5,178.06
6. Step 6: Final answer
   x = 3,891.87