Finding the Fourth Proportional to 28.34, 42.56 and 18.72

Step by Step Solution

1. Step 1: Write the proportion equation
   28.34 : 42.56 = 18.72 : x
2. Step 2: Convert to fraction form
   28.34/42.56 = 18.72/x
3. Step 3: Cross multiply
   28.34x = 42.56 × 18.72
4. Step 4: Simplify right side
   28.34x = 796.72
5. Step 5: Solve for x
   x = 796.72/28.34
6. Step 6: Final answer
   x = 28.11