Mean = (10 + 20 + 30 + 40 + 50) / 5 = 150 / 5 = 30

Mean = 30; Variance = [(10-30)² + (20-30)² + (30-30)² + (40-30)² + (50-30)²] / 5 = 200.

The mode is the number that appears most frequently. Here, 20 appears twice, so the mode is 20.

The mode is the number that appears most frequently. Here, 5 appears twice, so the mode is 5.

The mode is 4, as it appears most frequently (three times).

The mode is the number that appears most frequently. Here, 7 appears twice.

The mode is 10, as it appears most frequently (three times).

Mean = (12 + 15 + 20 + 25) / 4 = 72 / 4 = 18.

Mean = (1 + 2 + 3 + 4 + 5) / 5 = 15 / 5 = 3

Mean = (5 + 10 + 15 + 20 + 25) / 5 = 75 / 5 = 15.

Sorted data: 1, 2, 3, 4; Median = (2 + 3) / 2 = 2.5.