Finding the Fourth Proportional to 42.15, 63.29 and 18.12

Step by Step Solution

1. Step 1: Write the proportion equation
   42.15 : 63.29 = 18.12 : x
2. Step 2: Convert to fraction form
   42.15/63.29 = 18.12/x
3. Step 3: Cross multiply
   42.15x = 63.29 × 18.12
4. Step 4: Simplify right side
   42.15x = 1,146.86
5. Step 5: Solve for x
   x = 1,146.86/42.15
6. Step 6: Final answer
   x = 27.21