Finding the Fourth Proportional to 85.42, 128.13 and 42.67

Step by Step Solution

1. Step 1: Write the proportion equation
   85.42 : 128.13 = 42.67 : x
2. Step 2: Convert to fraction form
   85.42/128.13 = 42.67/x
3. Step 3: Cross multiply
   85.42x = 128.13 × 42.67
4. Step 4: Simplify right side
   85.42x = 5,467.31
5. Step 5: Solve for x
   x = 5,467.31/85.42
6. Step 6: Final answer
   x = 64.01