Finding the Fourth Proportional to 76.69, 105.72 and 65.05

Step by Step Solution

1. Step 1: Write the proportion equation
   76.69 : 105.72 = 65.05 : x
2. Step 2: Convert to fraction form
   76.69/105.72 = 65.05/x
3. Step 3: Cross multiply
   76.69x = 105.72 × 65.05
4. Step 4: Simplify right side
   76.69x = 6,877.09
5. Step 5: Solve for x
   x = 6,877.09/76.69
6. Step 6: Final answer
   x = 89.67