Finding the Fourth Proportional to 42.72, 64.08 and 28.56

Step by Step Solution

1. Step 1: Write the proportion equation
   42.72 : 64.08 = 28.56 : x
2. Step 2: Convert to fraction form
   42.72/64.08 = 28.56/x
3. Step 3: Cross multiply
   42.72x = 64.08 × 28.56
4. Step 4: Simplify right side
   42.72x = 1,830.12
5. Step 5: Solve for x
   x = 1,830.12/42.72
6. Step 6: Final answer
   x = 42.84