Finding the Fourth Proportional to 85.61, 128.91 and 65.50

Step by Step Solution

1. Step 1: Write the proportion equation
   85.61 : 128.91 = 65.50 : x
2. Step 2: Convert to fraction form
   85.61/128.91 = 65.50/x
3. Step 3: Cross multiply
   85.61x = 128.91 × 65.50
4. Step 4: Simplify right side
   85.61x = 8,443.61
5. Step 5: Solve for x
   x = 8,443.61/85.61
6. Step 6: Final answer
   x = 98.63