Finding the Fourth Proportional to 82.81, 124.28 and 42.21

Step by Step Solution

1. Step 1: Write the proportion equation
   82.81 : 124.28 = 42.21 : x
2. Step 2: Convert to fraction form
   82.81/124.28 = 42.21/x
3. Step 3: Cross multiply
   82.81x = 124.28 × 42.21
4. Step 4: Simplify right side
   82.81x = 5,245.86
5. Step 5: Solve for x
   x = 5,245.86/82.81
6. Step 6: Final answer
   x = 63.35