Finding the Fourth Proportional to 5,128.60, 7,077.20 and 2,890.42

Step by Step Solution

1. Step 1: Write the proportion equation
   5,128.60 : 7,077.20 = 2,890.42 : x
2. Step 2: Convert to fraction form
   5,128.60/7,077.20 = 2,890.42/x
3. Step 3: Cross multiply
   5,128.60x = 7,077.20 × 2,890.42
4. Step 4: Simplify right side
   5,128.60x = 20,456,080.42
5. Step 5: Solve for x
   x = 20,456,080.42/5,128.60
6. Step 6: Final answer
   x = 3,988.63