Finding the Fourth Proportional to 42.18, 63.18 and 18.09

Step by Step Solution

1. Step 1: Write the proportion equation
   42.18 : 63.18 = 18.09 : x
2. Step 2: Convert to fraction form
   42.18/63.18 = 18.09/x
3. Step 3: Cross multiply
   42.18x = 63.18 × 18.09
4. Step 4: Simplify right side
   42.18x = 1,142.93
5. Step 5: Solve for x
   x = 1,142.93/42.18
6. Step 6: Final answer
   x = 27.10