Question

13. Through previous results, it is observed that
70% of the students with atleast 90%
attendance attain A grade and 10% of irregular
students get A grade in their final examination
At the end of the session, it is found that x
students have atleast 90% attendance and y
students are irregular. If 14 students get A
grade in their final examination for that
session, represent it by a linear equation in x
and y. Use it to find the number of irregular
students if 16 students have atleast 90%
attendance.
Write the values reflected in this problem.​

Answer 1

Given :  70% of the students with atleast 90%  attendance attain A grade

10% of irregular  students get A grade

x  students have atleast 90% attendance and y  students are irregular

14 students get A

To Find : the number of irregular  students if 16 students have atleast 90% attendance

Solution:

70% of the students with atleast 90%  attendance attain A grade

10% of irregular  students get A grade

x  students have atleast 90% attendance

=> (70/100)x   = 0.7 x  will attain A grade

y  students are irregular.

=> (10/100)y = 0.1y  will attain A grade

attain A grade = 0.7x + 0.1y

14 students get A grade in their final examination

=>  0.7x + 0.1y  = 14

=> 7x + y = 140

16 students have atleast 90%  attendance.

=> x = 16

=> 7(16)+ y = 140

=> y = 28

Students with regular attendance get better grade,

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