Finding the Fourth Proportional to 111.78, 167.71 and 71.28

Step by Step Solution

1. Step 1: Write the proportion equation
   111.78 : 167.71 = 71.28 : x
2. Step 2: Convert to fraction form
   111.78/167.71 = 71.28/x
3. Step 3: Cross multiply
   111.78x = 167.71 × 71.28
4. Step 4: Simplify right side
   111.78x = 11,953.53
5. Step 5: Solve for x
   x = 11,953.53/111.78
6. Step 6: Final answer
   x = 106.94