Finding the Fourth Proportional to 142.16, 196 and 100.72

Step by Step Solution

1. Step 1: Write the proportion equation
   142.16 : 196 = 100.72 : x
2. Step 2: Convert to fraction form
   142.16/196 = 100.72/x
3. Step 3: Cross multiply
   142.16x = 196 × 100.72
4. Step 4: Simplify right side
   142.16x = 19,741.12
5. Step 5: Solve for x
   x = 19,741.12/142.16
6. Step 6: Final answer
   x = 138.87