Temperatures of cities as on 20.6.2006
What do these collections of data tell you?
The data about the temperatures of cities can tell us many things, For example, you can say that the highest maximum temperature was in Jammu on 20.06.2006 but it cannot tell us the city which had the highest maximum temperature during the year. To find that, we need to collect data regarding the highest maximum temperature reached in each of these cities during the year. In that case, the temperature chart of one particular date of the year, as given in the table will not be sufficient. This shows that a given collection of data may not give us specific information related to that data.
For this, we need to collect data keeping in mind that specific information. In the above case, the specific information needed by us was about the highest maximum temperature of the cities during the year, which we could not get from the Table. Thus, before collecting data, we need to know what we would use it for.
When the information was collected by the investigator herself or himself with a definite objective in her or his mind, the data obtained is called primary data.
When the information was gathered from a source which already had the information stored, the data obtained is called secondary data.
Such data, which has been collected by someone else in another context, needs to be used with great care ensuring that the source is reliable.
Shaalaa.com | Collection of Data
The class size of a distribution is 25 and the first class-interval is 200-224. There are seven
(i) Write the class-intervals.
(ii) Write the class-marks of each interval.
Classify the given data as primary or secondary data.
In our day to day life, we can collect the following data.
1. Number of females per 1000 males in various states of our country
2. Weights of students of our class
3. Production of wheat in the last 10 years in our country
4. Number of plants in our locality
5. Rainfall in our city in the last 10 years
The weights of new born babies (in kg) in a hospital on a particular day are as follows:
2.3, 2.2, 2.1, 2.7, 2.6, 3.0, 2.5, 2.9, 2.8, 3.1, 2.5, 2.8, 2.7, 2.9, 2.4
(i) Rearrange the weights in descending order.
(ii) Determine the highest weight.
(iii) Determine the lowest weight.
(iv) Determine the range.
(v) How many babies were born on that day?
(vi) How many babies weigh below 2.5 kg?
(vii) How many babies weigh more than 2.8 kg?
(viii) How many babies weigh 2.8 kg?
The final marks in mathematics of 30 students are as follows:
53, 61, 48, 60, 78, 68, 55, 100,67,90
44, 58, 52, 64, 98, 59, 70, 39, 50, 60
(i) Arrange these marks in the ascending order, 30 to 39 one group, 40 to 49 second group etc.
Now answer the following:
(ii) What is the highest score?
(iii) What is the lowest score?
(iv) What is the range?
(v) If 40 is the pass mark how many have failed?
(vi) How many have scored 75 or more?
(vii) Which observations between 50 and 60 have not actually appeared?
(viii) How many have scored less than 50?
Write the class-size in each of the following:
(i) 0 – 4, 5 – 9, 10 – 14
(ii) 10 – 19, 20 – 29, 30 – 39
(iii) 100 – 120, 120 – 140, 160 – 180
(iv) 0 – 0.25, 0.25 – 0.50, 0.50 – 0.75
(v) 5 – 5.01, 5.01 − 5.02, 5.02 – 5.03