Finding the Fourth Proportional to 7,210.12, 10,811.46 and 5,128.78

Step by Step Solution

1. Step 1: Write the proportion equation
   7,210.12 : 10,811.46 = 5,128.78 : x
2. Step 2: Convert to fraction form
   7,210.12/10,811.46 = 5,128.78/x
3. Step 3: Cross multiply
   7,210.12x = 10,811.46 × 5,128.78
4. Step 4: Simplify right side
   7,210.12x = 55,449,599.82
5. Step 5: Solve for x
   x = 55,449,599.82/7,210.12
6. Step 6: Final answer
   x = 7,690.52