Finding the Fourth Proportional to 42.05, 57.98 and 28.21

Step by Step Solution

1. Step 1: Write the proportion equation
   42.05 : 57.98 = 28.21 : x
2. Step 2: Convert to fraction form
   42.05/57.98 = 28.21/x
3. Step 3: Cross multiply
   42.05x = 57.98 × 28.21
4. Step 4: Simplify right side
   42.05x = 1,635.37
5. Step 5: Solve for x
   x = 1,635.37/42.05
6. Step 6: Final answer
   x = 38.89