If there are 20 boys out of 50 students in the class then find the percentage of boys.

The students of Class VIII of a school donated '2401 in all,for Prime Minister's National Relief Fund.Each student donated as many rupees as the number of students in the class.Find the number of students in the class.

A class teacher has the following absentee record of 40 students of a class for the whole term. Find the mean number of days a student was absent.

In a class there are 10 boys and 20 girls. The class teacher wants to select 1 boy and 1 girl to represent the class in a function. In how many can the teacher make this selection ?

If the frequency of dominant allele is 60%, find out the percentage of heterozygous individuals in the population.

In a class of 100 students there are 70 boys whose average marks in a subject is 75. If the average marks of the complete class is 72, then what is the average number of the girls ?

In a college, out of 4320 students, 2300 are girls. Find the ratio of (c) Number of boys to the total number of students.

In a college, out of 4320 students, 2300 are girls. Find the ratio of (b) Number of boys to the total number of girls.

The mean weight of a group of 9 students is 19 kg. If a boy of weight 29 kg is joined in the group, then find the mean weight of 10 students.