Finding the Fourth Proportional to 82.21, 123.20 and 34.15

Step by Step Solution

1. Step 1: Write the proportion equation
   82.21 : 123.20 = 34.15 : x
2. Step 2: Convert to fraction form
   82.21/123.20 = 34.15/x
3. Step 3: Cross multiply
   82.21x = 123.20 × 34.15
4. Step 4: Simplify right side
   82.21x = 4,207.28
5. Step 5: Solve for x
   x = 4,207.28/82.21
6. Step 6: Final answer
   x = 51.18