Finding the Fourth Proportional to 82.78, 124.04 and 42.18

Step by Step Solution

1. Step 1: Write the proportion equation
   82.78 : 124.04 = 42.18 : x
2. Step 2: Convert to fraction form
   82.78/124.04 = 42.18/x
3. Step 3: Cross multiply
   82.78x = 124.04 × 42.18
4. Step 4: Simplify right side
   82.78x = 5,232.01
5. Step 5: Solve for x
   x = 5,232.01/82.78
6. Step 6: Final answer
   x = 63.20