Finding the Fourth Proportional to 82.88, 124.48 and 78.72

Step by Step Solution

1. Step 1: Write the proportion equation
   82.88 : 124.48 = 78.72 : x
2. Step 2: Convert to fraction form
   82.88/124.48 = 78.72/x
3. Step 3: Cross multiply
   82.88x = 124.48 × 78.72
4. Step 4: Simplify right side
   82.88x = 9,799.07
5. Step 5: Solve for x
   x = 9,799.07/82.88
6. Step 6: Final answer
   x = 118.23