Finding the Fourth Proportional to 42.28, 55 and 42.28

Step by Step Solution

1. Step 1: Write the proportion equation
   42.28 : 55 = 42.28 : x
2. Step 2: Convert to fraction form
   42.28/55 = 42.28/x
3. Step 3: Cross multiply
   42.28x = 55 × 42.28
4. Step 4: Simplify right side
   42.28x = 2,325.40
5. Step 5: Solve for x
   x = 2,325.40/42.28
6. Step 6: Final answer
   x = 55