Finding the Fourth Proportional to 100.42, 150.56 and 81.18

Step by Step Solution

1. Step 1: Write the proportion equation
   100.42 : 150.56 = 81.18 : x
2. Step 2: Convert to fraction form
   100.42/150.56 = 81.18/x
3. Step 3: Cross multiply
   100.42x = 150.56 × 81.18
4. Step 4: Simplify right side
   100.42x = 12,222.46
5. Step 5: Solve for x
   x = 12,222.46/100.42
6. Step 6: Final answer
   x = 121.71