Finding the Fourth Proportional to 85.98, 129.08 and 42.72

Step by Step Solution

1. Step 1: Write the proportion equation
   85.98 : 129.08 = 42.72 : x
2. Step 2: Convert to fraction form
   85.98/129.08 = 42.72/x
3. Step 3: Cross multiply
   85.98x = 129.08 × 42.72
4. Step 4: Simplify right side
   85.98x = 5,514.30
5. Step 5: Solve for x
   x = 5,514.30/85.98
6. Step 6: Final answer
   x = 64.13