Finding the Fourth Proportional to 82.31, 123.42 and 28.19

Step by Step Solution

1. Step 1: Write the proportion equation
   82.31 : 123.42 = 28.19 : x
2. Step 2: Convert to fraction form
   82.31/123.42 = 28.19/x
3. Step 3: Cross multiply
   82.31x = 123.42 × 28.19
4. Step 4: Simplify right side
   82.31x = 3,479.21
5. Step 5: Solve for x
   x = 3,479.21/82.31
6. Step 6: Final answer
   x = 42.27