Finding the Fourth Proportional to 80.56, 120.84 and 42.12

Step by Step Solution

1. Step 1: Write the proportion equation
   80.56 : 120.84 = 42.12 : x
2. Step 2: Convert to fraction form
   80.56/120.84 = 42.12/x
3. Step 3: Cross multiply
   80.56x = 120.84 × 42.12
4. Step 4: Simplify right side
   80.56x = 5,089.78
5. Step 5: Solve for x
   x = 5,089.78/80.56
6. Step 6: Final answer
   x = 63.18