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9.  The heights of 10 girls were measured in cm and the results are as follows:
       135, 150, 139, 128, 151, 132, 146, 149, 143, 141.
 (i) What is the height of the tallest girl?(ii) What is the height of the shortest girl?
  (iii) What is the range of the data? (iv) What is the mean height of the girls?
   (v) How many girls have heights more than the mean height.

Given, Heights of 10 girls (in cm) =   Arranging the above data in ascending order =  (i) Height of the tallest girl =  (ii) Height of the shortest girl =  (iii) Range of the data =  (iv)  We know, Arithmetic mean =  Therefore, mean height of the girls is  (iv) Here, mean height =  And,  are more than  Therefore, 5  girls have height more than the average height.

8. The rainfall (in mm) in a city on 7 days of a certain week was recorded as follows:

(i) Find the range of the rainfall in the above data.
(ii) Find the mean rainfall for the week.
(iii) On how many days was the rainfall less than the mean rainfall.

Given, (i) Range = Maximum rainfall - Minimum rainfall (ii)  We know, Arithmetic mean =  Therefore, mean rainfall is  (iii) Here, mean =  Mon(0.0), Wed(2.1), Thu(0.0), Sat(5.5), Sun(1.0) are less than the mean Therefore, on 5 days, rainfall was less than the mean.

7. The enrolment in a school during six consecutive years was as follows:
        1555, 1670, 1750, 2013, 2540, 2820
       Find the mean enrolment of the school for this period.

Given, Enrolment during 6 consecutive years =   We know, Arithmetic mean Therefore, mean enrolment per year is 

6. The marks (out of 100) obtained by a group of students in a science test are 85, 76, 90, 85, 39, 48, 56, 95, 81 and 75. Find the:

      (i) Highest and the lowest marks obtained by the students.
      (ii) Range of the marks obtained.
     (iii) Mean marks obtained by the group.

Given, Marks obtained the students =  Arranging in ascending order =  (i) Highest marks obtained =  Lowest marks obtained =  (ii) Range of marks = Highest marks - Lowest marks (iii) We know, Arithmetic mean   Therefore, mean marks = 

5. Following table shows the points of each player scored in four games:
      
Now answer the following questions:
(i) Find the mean to determine A’s average number of points scored per game.
(ii) To find the mean number of points per game for C, would you divide the total points by 3 or by 4? Why?
(iii) B played in all the four games. How would you find the mean?
(iv) Who is the best performer?

Given, We know,    (i) Therefore, A's average number of points scored per game (ii) Number of games C played = 3 Therefore, to find the mean, we will divide by 3 Mean of C = (iii) Although he scored 0 in a match, he played all 4 games. Therefore, we will divide by 4. Mean of B =  (iv) Mean of A =  Mean of B =  Mean of C =   Since, A has the highest mean, A is the best performer.

4. A cricketer scores the following runs in eight innings: 58, 76, 40, 35, 46, 45, 0, 100. Find the mean score.

Given, Runs scored in eight innings = We know, Arithmetic mean  Therefore, mean score is 

3.  Find the mean of the first five whole numbers.

The first five whole numbers are     We know, Arithmetic mean   Therefore, mean of the first five whole numbers is 

2.   Organise the following marks in a class assessment, in a tabular form.
  4, 6, 7, 5, 3, 5, 4, 5, 2, 6, 2, 5, 1, 9, 6, 5, 8, 4, 6, 7
(i) Which number is the highest? (ii) Which number is the lowest?
(iii) What is the range of the data? (iv) Find the arithmetic mean.

Numbers Frequency 1 1 2 2 3 1 4 3 5 5 6 4 7 2 8 1 9 1 (i)  is the highest number. (ii)  is the lowest number (iii) Range of the data = Highest number - Lowest number (iv) Arithmetic mean =  Therefore, mean of the data is     
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