Finding the Fourth Proportional to 121.31, 167.33 and 72.18

Step by Step Solution

1. Step 1: Write the proportion equation
   121.31 : 167.33 = 72.18 : x
2. Step 2: Convert to fraction form
   121.31/167.33 = 72.18/x
3. Step 3: Cross multiply
   121.31x = 167.33 × 72.18
4. Step 4: Simplify right side
   121.31x = 12,077.88
5. Step 5: Solve for x
   x = 12,077.88/121.31
6. Step 6: Final answer
   x = 99.56