Which of the following are primary and secondary data?
i. Collection of the data about enrollment of students in your school for a period from 2001 to 2010.
ii. Height of students in your class recorded by physical education teacher.

Collect the details and find the probabilites of selecting a student from tenth standard in your school.

Which of the following are sets? Justify your answer (i) The collection of all the months of a year begimng with the letter "J". (ii) The collection of ten most talented writers of India. (iii) A team of eleven best cricket batsmen of the world. (iv) The collectionofall boys in your class. (v) The collection of all even integers.

Suppose that 120 students are studying in 4 sections of eleventh standard in a school. Let A denotes the set of students and B denote the set of the sections. Define a relation from A to B as "x related to y if the student x belongs to the section y". Is this relation a function ? What can you say about the inverse relation ? Explain your answer.

There are 40 students in Class X of a school of whom 25 are girls and 15 are boys. The class teacher has to select one student as a class representative. She writes the name of each student on separate cards, the cards being identical. Then she puts cards in a box and stirs them thoroughly. She then draws one card from the box. What is the probability that the name written on the card is the name of (i) a girl? (ii) a boy?

A student records the following data for the magnitudes (B) of the magnetic field at axial points at different distances x from the centre of a circular coil of radius 'a' carrying a current I. Verify (for any two) that these observations are in good agreement with the expected theoretical variation of B with x.