Finding the Fourth Proportional to 85.42, 128.06 and 59.77

Step by Step Solution

1. Step 1: Write the proportion equation
   85.42 : 128.06 = 59.77 : x
2. Step 2: Convert to fraction form
   85.42/128.06 = 59.77/x
3. Step 3: Cross multiply
   85.42x = 128.06 × 59.77
4. Step 4: Simplify right side
   85.42x = 7,653.21
5. Step 5: Solve for x
   x = 7,653.21/85.42
6. Step 6: Final answer
   x = 89.60