Finding the Fourth Proportional to 82.20, 123.28 and 28.10

Step by Step Solution

1. Step 1: Write the proportion equation
   82.20 : 123.28 = 28.10 : x
2. Step 2: Convert to fraction form
   82.20/123.28 = 28.10/x
3. Step 3: Cross multiply
   82.20x = 123.28 × 28.10
4. Step 4: Simplify right side
   82.20x = 3,464.17
5. Step 5: Solve for x
   x = 3,464.17/82.20
6. Step 6: Final answer
   x = 42.14