Finding the Fourth Proportional to 142.42, 213.69 and 78.22

Step by Step Solution

1. Step 1: Write the proportion equation
   142.42 : 213.69 = 78.22 : x
2. Step 2: Convert to fraction form
   142.42/213.69 = 78.22/x
3. Step 3: Cross multiply
   142.42x = 213.69 × 78.22
4. Step 4: Simplify right side
   142.42x = 16,714.83
5. Step 5: Solve for x
   x = 16,714.83/142.42
6. Step 6: Final answer
   x = 117.36