Finding the Fourth Proportional to 80.67, 120.90 and 42.15

Step by Step Solution

1. Step 1: Write the proportion equation
   80.67 : 120.90 = 42.15 : x
2. Step 2: Convert to fraction form
   80.67/120.90 = 42.15/x
3. Step 3: Cross multiply
   80.67x = 120.90 × 42.15
4. Step 4: Simplify right side
   80.67x = 5,095.94
5. Step 5: Solve for x
   x = 5,095.94/80.67
6. Step 6: Final answer
   x = 63.17