Finding the Fourth Proportional to 82.20, 123.18 and 60.72

Step by Step Solution

1. Step 1: Write the proportion equation
   82.20 : 123.18 = 60.72 : x
2. Step 2: Convert to fraction form
   82.20/123.18 = 60.72/x
3. Step 3: Cross multiply
   82.20x = 123.18 × 60.72
4. Step 4: Simplify right side
   82.20x = 7,479.49
5. Step 5: Solve for x
   x = 7,479.49/82.20
6. Step 6: Final answer
   x = 90.99