Need help on this math question. Please help me

:24% of students in a class are girls. if there are less than 30 students in this class, how many students are there? how many girls are there?

The weight v of an object on venus varies directly with its weight e on earth. a person weighing 120 lb on earth would weigh 106 lb on venus. how much would a person weighing 150 lb on earth weigh on venus?

The coverage of a base station of a telecommunication company forms a disk with a radius of (kilometers). let be the distance of a cellphone from a base station. assume that the location of cellphones in use are randomly uniformly distributed within the disk. calculate the mean and variance for the random variable.