Thirty children were asked about the number of hours they watched TV programmes in the previous week. The results were found as follows:

(i) Make a grouped frequency distribution table for this data, taking class width 5 and one of the class intervals as 5 - 10. (ii) How many children watched television for 15 or more hours a week ?

A company manufactures car batteries of a particular type. The lives in years) of 40 such batteries were recorded as follows: Construct a grouped frequency distribution table for this data, using class intervals of size 0.5 starting from the interval 2 - 2.5.

The heights of 50 students, measured to the nearest centimetres, have been found to be as follows: (i) Represent the data given above by a grouped frequency distribution table, taking the class intervals as 160 - 165,165-170, etc. (ii) What can you conclude about their heights from the table ?

A study was conducted to find out the concentration of sulphur dioxide in the air in parts per million (ppm) of a certain city. The data obtained for 30 days is as follows: (i) Make a grouped frequency distribution table for this data with class intervals as 0.00 -0.04, 0.04 -0.08, and so on. (ii) For how many days, was the concentration of sulphur dioxide more than 0.11 parts per million ?

The distance (in km) of 40 engineers from their residence to their place of work were found as follows : Construct a grouped frequency distribution table with class size 5 for the data given above taking the first interval as 0-5 (5 not included). What main features do you observe from this tabular representation ?

100 surnames were randomly picked up from a local telephone directory and a frequency distribution of the number of letters in the English alphabet in the surnames was found as follows: (i) Draw a histogram to depict the given information, (ii) Write the class interval in which the maximum number of surnames lie.

5 people were asked about the time in a week they spend in doing social work in their community. They said 10, 7, 13, 20 and 15 hours, respectively. Find the mean (or average) time in a week devoted by them for social work.

In a particular section of Class IX, 40 students were asked about the month of their birth and the following graph was prepared for the data so obtained : Observe the bar graph given above and answer the following questions: ( i ) How many students were born in the month of November? (ii) in which month were the maximum number of students born ?

(Manufacturing problem) A manufacturer has three machines I, II and III installed in his factory. Machines I and II are capable of being operated for at most 12 hours whereas machine III must be operated for atleast 5 hours a day. She produces only two items M and N each requiring the use of all the three machines. The number of hours required for producing 1 unit of each of M and N on the three machines are given in the following table : She makes a profit of Rs. 600 and Rs. 400 on items M and N respectively. How many of each should she produce so as to maximise her profit assuming that she can sell all the items that she produced? What will be the maximum profit ?

A TV channel or organised SMS (Short Message Service) poll on prohibition on smoking giving options like A- complete prohibition, B- prohibited in public places only, C- not necessary, SMS results in one hour were Represent the amount of data is grouped frequency distribution table. How many appropriate answers were received? What was the majority of peoples' opinion?

A factory makes tennis rackets and cricket bats. A tennis racket takes 1.5 hours of machine time and 3 hours of craftman's time in its making while a cricket bat takes 3 hour of machine time and 1 hour of craftman's time.In a day, the factory has the availability of not more than 42 hours of machine time and 24 hours of craftman's time. (i) What number of rackets and bats must be made if the factory is to work at full capacity? (ii) If the profit on a racket and on a bat is Rs. 20 and Rs. 10 respectivelh, find the maximum profit of the factory when it works at full capacity.