Tales by Dots and Lines Class 8 Short Question Answer

Tales by Dots and Lines Class 8 Short Question Answer

Tales by Dots and Lines Class 8 Short Question Answer

Question 1.

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 mean marks obtained by the group.

Solution:

Mean marks

= 73.

Question 2.

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.

Solution:

Sum of the enrolment during six consecutive years

= 1555 + 1670 + 1750 + 2013 + 2540 + 2820

= 12348.

Mean enrolment = [latex]\frac{12348}{6}[/latex] = 2058.

Question 3.

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

Find the mean rainfall for the week.

Solution:

Sum of the rainfall during the week = 0.0 + 0.0 + 1.0 + 2.1 + 5.5 + 12.2 + 20.5

= 41.3 mm

Mean = [latex]\frac{41.3}{7}[/latex] = 5.9 mm.

(iii) For five days, the rainfall was less than the mean rainfall.

Question 4.

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.

What is the mean height of the girls ?

Solution:

Arranging the heights (in cm) in the ascending order, we have : 128, 132, 135, 139, 141, 143, 146, 149, 150, 151.

Mean height

= 141.4 cm.

Question 5.

Your friend found the median of a given data. Describe and correct your , friend’s error if any :

35, 32, 35, 42, 38, 32, 34

Median = 42

Solution:

Arranging the given data in ascending order, we have :

32, 32, 34, 35, 35, 38, 42

Since median is the middle most observation.

So, median 35

Median is 35, not 42.