Mean And Median Class-9 Concise ICSE Maths Selina Solutions Chapter-19. We provide step by step Solutions of Exercise / lesson-19 Mean And Median ( for ungroup data only ) for ICSE Class-9 Concise Selina Mathematics by R K Bansal.
Our Solutions contain all type Questions with Exe-19 A, Exe-19 B, Exe-19 C, to develop skill and confidence. Visit official Website CISCE for detail information about ICSE Board Class-9 Mathematics .
Mean And Median Class-9 Concise ICSE Maths Selina Solutions Chapter-19
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Exe-19 A Mean And Median Class-9 Concise ICSE Maths Selina Solutions
Question 1
Find the mean of 43, 51, 50, 57 and 54.
Answer
Question 2
Find the mean of first six natural numbers.
Answer
Question 3
Find the mean of first ten odd natural number.
Answer
Question 4
Find the mean of all factors of 10.
Answer
Question 5
Find the mean of x + 3, x + 5, x + 7, x + 9 and x + 11.
Answer
Question 6
If different values of variable x are 9.8, 5.4, 3.7, 1.7, 1.8, 2.6, 2.8, 8.6, 10.5 and 11.1; find
(i) the mean (ii) the value of ……….
Answer
Question 7
The mean of 15 observations is 32. Find the resulting mean, if each observation is :
(i) Increased by 3
(ii) Decreased by 7
(iii) Multiplied by 2
(iv) Divided by 0.5
(v) Increased by 60%
(vi) Decreased by 20%
Answer
Question 8
The mean of 5 numbers is 18. If one number is excluded, the mean of remaining number becomes 16. Find the excluded number.
Answer
Question 9
If the mean of observations x, x + 2, x + 4, x + 6 and x + 8 is 11, find:
(i) The value of x;
(ii) The mean of first three observations.
Answer
Question 10
The mean of 100 observations is 40. It is found that an observation 53 was misread as 83. Find the correct mean.
Answer
Question 11
The mean of 200 items was 50. Later on, it was discovered that two items were misread as 92 and 8 instead of 192 and 88. Find the correct mean.
Answer
Question 12
Find the mean of 75 numbers, if the mean of 45 of them is 18 and the mean of the remaining ones is 13.
Answer
Question 13
The mean weight of 120 students of a school is 52.75 kg. If the mean weight of 50 of them is 51 kg, find the mean weight of the remaining students.
Answer
Question 14
The mean marks (out of 100) of boys and girls in an examination are 70 and 73 respectively. If the mean marks of all the students in that examination is 71, find the ratio of the number of boys to the number of girls.
Answer
Question 15
Find x if 9, x, 14, 18 x, x, 8, 10 and 4 have a mean of 11.
Answer
Question 16
In a series of tests, A appeared for 8 tests. Each test was marked out of 30 and averages 25. However, while checking his files, A could only find 7 of the 8 tests. For these he scored 29, 26, 18, 20, 27, 24 and 29. Determine how many marks he scored for the eighth test.
Answer
Total number of tests = 8
Average score of A = 25
Let the score of 8th test be x.
Then, total score of 8 tests = 29 + 26 + 18 + 20 + 27 + 24 + 29 + x
Now, we have
⇒ 25 x 8 =173 + x
⇒ x +173 = 200
⇒ x = 200 – 173
⇒ x = 27
Thus, A scored 27 marks in the eights test.
Mean And Median Class-9 Concise ICSE Maths Selina Solutions Exercise 19(B)
Question 1
Find the median of:
(i) 25, 16, 26, 16, 32, 31, 19, 28 and 35
(ii) 241, 243, 347, 350, 327, 299, 261, 292, 271, 258 and 257
(iii) 63, 17, 50, 9, 25, 43, 21, 50, 14 and 34
(iv) 233, 173, 189, 208, 194, 204, 194, 185, 200 and 220.
Answer
Question 2
The following data have been arranged in ascending order. If their median is 63, find the value of x.
34, 37, 53, 55, x, x + 2, 77, 83, 89 and 100.
Answer
Question 3
In 10 numbers, arranged in increasing order, the 7th number is increased by 8, how much will the median be changed?
Answer
Question 4
Out of 10 students, who appeared in a test, three secured less than 30 marks and 3 secured more than 75 marks. The marks secured by the remaining 4 students are 35, 48, 66 and 40. Find the median score of the whole group.
Answer
Question 5
The median of observations 10, 11, 13, 17, x + 5, 20, 22, 24 and 53 (arranged in ascending order) is 18; find the value of x.
Answer
Selina Solutions Exe-19 C Mean And Median Class-9 Concise ICSE Maths
Question 1
Find the mean of 8, 12, 16, 22, 10 and 4. Find the resulting mean, if each of the observations, given above, be:
(i) multiplied by 3.
(ii) divided by 2.
(iii) multiplied by 3 and then divided by 2.
(iv) increased by 25%
(v) decreased by 40%
Answer
Question 2
The mean of 18, 24, 15, 2x + 1 and 12 is 21. Find the value of x.
Answer
Question 3
The mean of 6 numbers is 42. If one number is excluded, the mean of remaining number is 45. Find the excluded number.
Answer
Question 4
The mean of 10 numbers is 24. If one more number is included, the new mean is 25. Find the included number.
Answer
Question 5
The following observations have been arranged in ascending order. If the median of the data is 78, find the value of x.
44, 47, 63, 65, x + 13, 87, 93, 99, 110.
Answer
Question 6
The following observations have been arranged in ascending order. If the median of these observations is 58, find the value of x.
24, 27, 43, 48, x – 1, x + 3, 68, 73, 80, 90.
Answer
Question 7
Find the mean of the following data:
30, 32, 24, 34, 26, 28, 30, 35, 33, 25
(i) Show that the sum of the deviations of all the given observation from the mean is zero.
(ii) Find the median of the given data.
Answer
Question 8
Find the mean and median of the data:
35, 48, 92, 76, 64, 52, 51, 63 and 71.
If 51 is replaced by 66, what will be the new median?
Answer
Question 9
The mean of x, x + 2, x + 4, x + 6 and x + 8 is 11, find the mean of the first three observations.
Answer
Question 10
Find the mean and median of all the positive factors of 72.
Answer
Question 11
The mean weight of 60 students in a class is 40 kg. The mean weight of boys is 50 kg while that of girls is 30 kg. Find the number of boys and girls in the class.
Answer
Total number of students = 60
Mean weight of 60 students = 40
Let the number of boys = x
Then, number of girls = 60 – x
2400 = 50 x + 1800 – 30x
20 x = 600
x = 30
so 60- x
60-30
30
Hence, the number of boys is 30 and the number of girls is also 30.
Question 12
The average of n numbers x1, x2, x3 ….. xn is A. If x1 is replaced by (x+ α)x1, x2, is replaced by (x+ α)x2 and so on. Find the new average.
Answer
Mean of n numbers = A
Question 13
The heights (in cm) of the volley- ball players from team A and team B were recorded as:
Team A: 180, 178, 176, 181, 190, 175, 187
Team B: 174, 175, 190, 179, 178, 185, 177
Which team had the greater average height?
Find the median of team A and team B.
Answer
Total number of players in each team = 7
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