Finding the Fourth Proportional to 89.30, 122.72 and 85.28

Step by Step Solution

1. Step 1: Write the proportion equation
   89.30 : 122.72 = 85.28 : x
2. Step 2: Convert to fraction form
   89.30/122.72 = 85.28/x
3. Step 3: Cross multiply
   89.30x = 122.72 × 85.28
4. Step 4: Simplify right side
   89.30x = 10,464.87
5. Step 5: Solve for x
   x = 10,464.87/89.30
6. Step 6: Final answer
   x = 117.18