Finding the Fourth Proportional to 82.80, 124.15 and 42.30

Step by Step Solution

1. Step 1: Write the proportion equation
   82.80 : 124.15 = 42.30 : x
2. Step 2: Convert to fraction form
   82.80/124.15 = 42.30/x
3. Step 3: Cross multiply
   82.80x = 124.15 × 42.30
4. Step 4: Simplify right side
   82.80x = 5,251.55
5. Step 5: Solve for x
   x = 5,251.55/82.80
6. Step 6: Final answer
   x = 63.42