Finding the Fourth Proportional to 111.90, 167.91 and 71.31

Step by Step Solution

1. Step 1: Write the proportion equation
   111.90 : 167.91 = 71.31 : x
2. Step 2: Convert to fraction form
   111.90/167.91 = 71.31/x
3. Step 3: Cross multiply
   111.90x = 167.91 × 71.31
4. Step 4: Simplify right side
   111.90x = 11,973.66
5. Step 5: Solve for x
   x = 11,973.66/111.90
6. Step 6: Final answer
   x = 107.00