Finding the Fourth Proportional to 142.56, 196.72 and 90.12

Step by Step Solution

1. Step 1: Write the proportion equation
   142.56 : 196.72 = 90.12 : x
2. Step 2: Convert to fraction form
   142.56/196.72 = 90.12/x
3. Step 3: Cross multiply
   142.56x = 196.72 × 90.12
4. Step 4: Simplify right side
   142.56x = 17,728.41
5. Step 5: Solve for x
   x = 17,728.41/142.56
6. Step 6: Final answer
   x = 124.36