Finding the Fourth Proportional to 81.19, 121.72 and 42.69

Step by Step Solution

1. Step 1: Write the proportion equation
   81.19 : 121.72 = 42.69 : x
2. Step 2: Convert to fraction form
   81.19/121.72 = 42.69/x
3. Step 3: Cross multiply
   81.19x = 121.72 × 42.69
4. Step 4: Simplify right side
   81.19x = 5,196.23
5. Step 5: Solve for x
   x = 5,196.23/81.19
6. Step 6: Final answer
   x = 64.00