Finding the Fourth Proportional to 85.42, 128.04 and 61.06

Step by Step Solution

1. Step 1: Write the proportion equation
   85.42 : 128.04 = 61.06 : x
2. Step 2: Convert to fraction form
   85.42/128.04 = 61.06/x
3. Step 3: Cross multiply
   85.42x = 128.04 × 61.06
4. Step 4: Simplify right side
   85.42x = 7,818.12
5. Step 5: Solve for x
   x = 7,818.12/85.42
6. Step 6: Final answer
   x = 91.53