Finding the Fourth Proportional to 142.22, 196.16 and 100.78

Step by Step Solution

1. Step 1: Write the proportion equation
   142.22 : 196.16 = 100.78 : x
2. Step 2: Convert to fraction form
   142.22/196.16 = 100.78/x
3. Step 3: Cross multiply
   142.22x = 196.16 × 100.78
4. Step 4: Simplify right side
   142.22x = 19,768.01
5. Step 5: Solve for x
   x = 19,768.01/142.22
6. Step 6: Final answer
   x = 138.99