Finding the Fourth Proportional to 82.48, 123.68 and 56.78

Step by Step Solution

1. Step 1: Write the proportion equation
   82.48 : 123.68 = 56.78 : x
2. Step 2: Convert to fraction form
   82.48/123.68 = 56.78/x
3. Step 3: Cross multiply
   82.48x = 123.68 × 56.78
4. Step 4: Simplify right side
   82.48x = 7,022.55
5. Step 5: Solve for x
   x = 7,022.55/82.48
6. Step 6: Final answer
   x = 85.14