Finding the Fourth Proportional to 80.64, 121.01 and 42.15

Step by Step Solution

1. Step 1: Write the proportion equation
   80.64 : 121.01 = 42.15 : x
2. Step 2: Convert to fraction form
   80.64/121.01 = 42.15/x
3. Step 3: Cross multiply
   80.64x = 121.01 × 42.15
4. Step 4: Simplify right side
   80.64x = 5,100.57
5. Step 5: Solve for x
   x = 5,100.57/80.64
6. Step 6: Final answer
   x = 63.25