M l aggarwal understanding icse mathematics class 9 Solutions for Chapter 20 statistics

Find the mean of 8, 6, 10, 12, 1, 3, 4, 4.

The enrollment of a school during six consecutive years was as follows:

1620, 2060, 2540, 3250, 3500, 3710.

Find the mean enrollment.

Find the mean of the first twelve natural numbers

(i) Find the mean of the first six prime numbers.

(ii) Find the mean of the first seven odd prime numbers.

(i)The marks (out of 100) obtained by a group of students in a Mathematics test are 81, 72, 90,

90, 85, 86, 70, 93 and 71. Find the mean marks obtained by a group of students.

(ii) The mean of the age of three students Vijay, Rahul, and Rakhi is 15 years. If their ages are in

the ratio 4: 5: 6 respectively, then find their ages.

The mean of 5 numbers is 20. If one number is excluded, the mean of the remaining numbers

becomes 23. Find the excluded number.

The mean of 25 observations is 27. If one observation is included, the mean still remains 27.

Find the included observation.

The mean of 5 observations is 15. If the mean of first three observations is 14 and that

of the last three is 17, find the third observation.

The mean of 8 variates is 10.5. If seven of them are 3, 15, 7, 19, 2, 17, and 8 then find

the 8th variate.

The mean weight of 8 students is 45.5 kg. Two more students having weights 41.7 kg and 53.3

kg join the group. What is the new mean weight?

Mean of 9 observations was found to be 35. Later on, it was detected that an observation 81

was misread as 18. Find the correct mean of the observations.

A student scored the following marks in 11 questions of a question paper:

7, 3, 4, 1, 5, 8, 2, 2, 5, 7, 6.

Find the median marks.

In a Science test given to a group of students, the marks scored by them (out of 100) are

1, 39, 52, 48, 54, 62, 46, 52, 40, 96, 42, 40, 98, 60, 52.

Find the mean and median of this data

The points scored by a Kabaddi team in a series of matches are as follow

17, 2, 5, 27, 15, 8, 14, 10, 48, 10, 7, 24, 8, 28, 18.

Find the mean and the median of the points scored by the Kabaddi team

The following observations have been arranged in ascending order. If the median

the data is 44.5, find the value of x.

17, 21, 23, 29, 39, 40, x, 50, 51, 54, 59, 67, 91, 93

The following observations have been arranged in ascending order. If the median

the data is 13, find the value of x.

3, 6, 7, 10, x, x + 4, 19, 20, 25, 28.

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

(i)marks scored (out of 50) in a test.

(ii) the daily temperature of your city.

(iii) sizes of shoes.

(iv)distance traveled by a man.

(v)time.

A Explain the meaning of the following terms :

(i) variate

(ii) class size

(iii) classmark

(iv) class limits

(v) true class limits

(vi) frequency of a class

(vii) cumulative frequency of a class.

Fill in the blanks:

(i) The number of observations in a particular class is called …… of the class.

(ii) The difference between the class marks of two consecutive classes is the ….. of the class.

(iii) The range of the data 16, 19, 23, 13, 11, 25, 18 is …

(iv) The mid-point of the class interval is called its …

(v) The class mark of the class 4 – 9 is ….

. The marks obtained (out of 50) by 40 students in a test are given below:

28, 31, 45, 03, 05, 18, 35, 46, 49, 17, 10, 28, 31, 36, 40, 44, 47, 13, 19, 25, 24, 31, 38, 32,

27, 19, 25, 28, 48, 15, 18, 31, 37, 46, 06, 01, 20, 10, 45, 02.

(i) Taking class intervals 1- 10, 11 – 20, .., construct a tally chart and a frequency

distribution table.

(ii) Convert the above distribution to continuous distribution.

(iii) State the true class limits of the third class.

(iv) State the class mark of the fourth class.

The water bills (in rupees) of 32 houses in a locality are given below. Construct a

frequency distribution table with a class size of 10.

80, 48, 52, 78, 103, 85, 37, 94, 72, 73, 66, 52, 92, 85, 78, 81, 64, 60, 75, 78, 108, 63, 71, 54,

59, 75, 100, 103, 35, 89, 95, 73.