A group of 65 students of class XI have their average height is 150.4 cm with coefficient of variance 2.5%. What is the standard deviation of their height?

A class has 15 students whose ages are 14,17,15,14,21,17,19,20,16,18,20,17,16,19 and 20 years.One student is selected in such a manner that each has the same chance of being chosen and the age X of the selected student is recorded.What is the probability distribution of the random variable X?Find mean,variance and standard deviation of X.

Given the heights (in cm) of two group of students: Group A: 131 cm, 150 cm, 147 cm, 138 cm, 144 cm. Group B: 139 cm, 148 cm, 132 cm, 151 cm, 140 cm. Which of the following is/are the true? (I) The range the heights of the two groups of students are the same. (II) The mean of the heights of the two groups of students are the same.