Finding the Fourth Proportional to 85.82, 128.45 and 59.99

Step by Step Solution

1. Step 1: Write the proportion equation
   85.82 : 128.45 = 59.99 : x
2. Step 2: Convert to fraction form
   85.82/128.45 = 59.99/x
3. Step 3: Cross multiply
   85.82x = 128.45 × 59.99
4. Step 4: Simplify right side
   85.82x = 7,704.77
5. Step 5: Solve for x
   x = 7,704.77/85.82
6. Step 6: Final answer
   x = 89.78