Finding the Fourth Proportional to 31.02, 42.58 and 28.42

Step by Step Solution

1. Step 1: Write the proportion equation
   31.02 : 42.58 = 28.42 : x
2. Step 2: Convert to fraction form
   31.02/42.58 = 28.42/x
3. Step 3: Cross multiply
   31.02x = 42.58 × 28.42
4. Step 4: Simplify right side
   31.02x = 1,210.00
5. Step 5: Solve for x
   x = 1,210.00/31.02
6. Step 6: Final answer
   x = 39.00