Finding the Fourth Proportional to 72.16, 108.18 and 31.55

Step by Step Solution

1. Step 1: Write the proportion equation
   72.16 : 108.18 = 31.55 : x
2. Step 2: Convert to fraction form
   72.16/108.18 = 31.55/x
3. Step 3: Cross multiply
   72.16x = 108.18 × 31.55
4. Step 4: Simplify right side
   72.16x = 3,412.54
5. Step 5: Solve for x
   x = 3,412.54/72.16
6. Step 6: Final answer
   x = 47.29