Finding the Fourth Proportional to 85.50, 128.16 and 31.35

Step by Step Solution

1. Step 1: Write the proportion equation
   85.50 : 128.16 = 31.35 : x
2. Step 2: Convert to fraction form
   85.50/128.16 = 31.35/x
3. Step 3: Cross multiply
   85.50x = 128.16 × 31.35
4. Step 4: Simplify right side
   85.50x = 4,017.82
5. Step 5: Solve for x
   x = 4,017.82/85.50
6. Step 6: Final answer
   x = 46.99