Finding the Fourth Proportional to 76.81, 105.82 and 53.15

Step by Step Solution

1. Step 1: Write the proportion equation
   76.81 : 105.82 = 53.15 : x
2. Step 2: Convert to fraction form
   76.81/105.82 = 53.15/x
3. Step 3: Cross multiply
   76.81x = 105.82 × 53.15
4. Step 4: Simplify right side
   76.81x = 5,624.07
5. Step 5: Solve for x
   x = 5,624.07/76.81
6. Step 6: Final answer
   x = 73.23