Finding the Fourth Proportional to 42.18, 63.12 and 31.98

Step by Step Solution

1. Step 1: Write the proportion equation
   42.18 : 63.12 = 31.98 : x
2. Step 2: Convert to fraction form
   42.18/63.12 = 31.98/x
3. Step 3: Cross multiply
   42.18x = 63.12 × 31.98
4. Step 4: Simplify right side
   42.18x = 2,018.58
5. Step 5: Solve for x
   x = 2,018.58/42.18
6. Step 6: Final answer
   x = 47.86