Finding the Fourth Proportional to 85.30, 128.06 and 42.06

Step by Step Solution

1. Step 1: Write the proportion equation
   85.30 : 128.06 = 42.06 : x
2. Step 2: Convert to fraction form
   85.30/128.06 = 42.06/x
3. Step 3: Cross multiply
   85.30x = 128.06 × 42.06
4. Step 4: Simplify right side
   85.30x = 5,386.20
5. Step 5: Solve for x
   x = 5,386.20/85.30
6. Step 6: Final answer
   x = 63.14