Finding the Fourth Proportional to 171.89, 237.42 and 128.42

Step by Step Solution

1. Step 1: Write the proportion equation
   171.89 : 237.42 = 128.42 : x
2. Step 2: Convert to fraction form
   171.89/237.42 = 128.42/x
3. Step 3: Cross multiply
   171.89x = 237.42 × 128.42
4. Step 4: Simplify right side
   171.89x = 30,489.48
5. Step 5: Solve for x
   x = 30,489.48/171.89
6. Step 6: Final answer
   x = 177.38