Finding the Fourth Proportional to 42.76, 64.12 and 18.72

Step by Step Solution

1. Step 1: Write the proportion equation
   42.76 : 64.12 = 18.72 : x
2. Step 2: Convert to fraction form
   42.76/64.12 = 18.72/x
3. Step 3: Cross multiply
   42.76x = 64.12 × 18.72
4. Step 4: Simplify right side
   42.76x = 1,200.33
5. Step 5: Solve for x
   x = 1,200.33/42.76
6. Step 6: Final answer
   x = 28.07