Finding the Fourth Proportional to 143.89, 215.56 and 75.31

Step by Step Solution

1. Step 1: Write the proportion equation
   143.89 : 215.56 = 75.31 : x
2. Step 2: Convert to fraction form
   143.89/215.56 = 75.31/x
3. Step 3: Cross multiply
   143.89x = 215.56 × 75.31
4. Step 4: Simplify right side
   143.89x = 16,233.82
5. Step 5: Solve for x
   x = 16,233.82/143.89
6. Step 6: Final answer
   x = 112.82