Finding the Fourth Proportional to 82.16, 122.42 and 78.48

Step by Step Solution

1. Step 1: Write the proportion equation
   82.16 : 122.42 = 78.48 : x
2. Step 2: Convert to fraction form
   82.16/122.42 = 78.48/x
3. Step 3: Cross multiply
   82.16x = 122.42 × 78.48
4. Step 4: Simplify right side
   82.16x = 9,607.52
5. Step 5: Solve for x
   x = 9,607.52/82.16
6. Step 6: Final answer
   x = 116.94