What are primary data and secondary data ? Which of the two are more reliable and why?

Fill in the blanks

(i) The difference between the maximum and minimum observations in a data is called the ………… of the data.

(ii) The number of observations in a class-interval is called the ………… of the interval.

(iii) The mid-point of a class-interval is called the ………… of the interval.

(iv) Lower-limit of the class-interval 24-30 is …………

(v) Upper limit of the class-interval 16-20 is …………

(vi) The class-mark of the class-interval is 20-30 is …………

(vii) The class-mark of the class-interval 9.5-19.5 is …………

The class marks of a frequency distribution are 28, 34, 40, 46, 52. Find the class-size and all the class intervals.

State which of the following variables are continuous and which are discrete :

(i) Marks obtained by the students of a class in a test.

(ii) Daily maximum temperature of a city.

(iii) I.Q. of a students of a class.

(iv) Weights of players of a Volley-ball team.

(v) Number of car-accidents in a city.

(vi) Distance travelled by a train.

(vii) Time taken by runners in a race.

(viii) Sizes of shoes sold in a shoe-store.

(ix) Number of patients in a hospital per day.