Finding the Fourth Proportional to 28.70, 42.72 and 28.29

Step by Step Solution

1. Step 1: Write the proportion equation
   28.70 : 42.72 = 28.29 : x
2. Step 2: Convert to fraction form
   28.70/42.72 = 28.29/x
3. Step 3: Cross multiply
   28.70x = 42.72 × 28.29
4. Step 4: Simplify right side
   28.70x = 1,208.55
5. Step 5: Solve for x
   x = 1,208.55/28.70
6. Step 6: Final answer
   x = 42.12