Finding the Fourth Proportional to 42.72, 58.97 and 28.91

Step by Step Solution

1. Step 1: Write the proportion equation
   42.72 : 58.97 = 28.91 : x
2. Step 2: Convert to fraction form
   42.72/58.97 = 28.91/x
3. Step 3: Cross multiply
   42.72x = 58.97 × 28.91
4. Step 4: Simplify right side
   42.72x = 1,704.82
5. Step 5: Solve for x
   x = 1,704.82/42.72
6. Step 6: Final answer
   x = 39.91