Important Questions for Class 7 Chapter 9-Rational Numbers

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Important questions based on NCERT syllabus for Class 7 Chapter 9 - Rational Numbers:

Question 1: An investor invested 20cr in a company for the development of a mobile application. Company distributed this money among various departments to cover up the needs, one-sixth of invested money is allocated to advertisement team . Two third of remaining money was given to development team. In development team there are two sub teams namely Graphics and content team. Among them it is distributed in such a way that content team will get 3/2times more money than that of graphics team. Find the money allocated to each team separately.
Solution:
Total money invested = 20cr Amount allocated to advertisement team = 20 x (1/4)= 5cr
Remaining amount = 20-5=15cr;
Two third of 15 cr is allocated for development team= 15 x 2/3 = 10cr
Let graphics team got x ,then content team got 3/2x. By solving x +3/2x =10 ;
x=4
Hence, amount allocated for graphics and content team were 4cr and 6cr respectively.

Question 2: Write the comment on the following rational numbers whether they are equal or greater or less than 19/26. The numbers are 247/338, 26/32 and 19/21.
Solution:
When we multiply by 13 in the numerator and the denominator we get 247/338 , therefore, 19/26 = 247/338.
By inspection, when numerator is same and denominator is different then the fraction having large value of denominator is smaller than the fraction having less value of denominator.
Hence 19/26< 19/21.
For comparing 19/26 and 13/16 we have to make the denominator of both the
fraction by taking LCM of 26 & 16 = 416.
19×16/26×16 = 304/416 ,
13×26/16×26 = 338/416 ;
338 > 304
Hence, 26/32 > 19/26

Question 3: Amit used to be on the playground 4 (1/2) times as much as his brother. His parents threatened him, so, he cut down to 1(1/3) of the time he used to play. How many times as much as his brother is he now on the ground?
Solution:
Amit played 9/2 times of his brother.
After threaten, duration of Amit play = 9/2-4/3 = 21/6 = 7/2
So, now Amit plays 7/2 times of his brother.