Question 22 To receive Grade ‘A’ in a course, one must obtain an average of 90 marks or more in five examinations (each of 100 marks).
If Sunita’s marks in first four examinations are 87, 92, 94 and 95, find minimum marks that Sunita must obtain in fifth examination to get grade ‘A’ in the course.
Class X1 - Maths -Linear Inequalities Page 122
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Answered by
0
let us assume that she got x in 5th exam
so 87+92+94+95+x/500×100=90
179+189+x/5=90
358+x=90×5
358+x=450
x=450-358
=92
so 87+92+94+95+x/500×100=90
179+189+x/5=90
358+x=90×5
358+x=450
x=450-358
=92
Answered by
7
let Sunita got x marks in the 5th exam.
so, average marks obtained by Sunita = sum of marks of all exams / number of exams .
= ( 87 + 92 + 94 + 95 + x)/5
= ( 368 + x)/5
now, a/c to question,
Sunita wants to obtain grade A for that average marks should be greater than 90 or equal to 90.
e.g. (368+x)/5 ≥ 90
368 + x ≥ 90×5 = 450
368 + x ≥ 450
x ≥ 82
hence, Sunita Should got greater than or equal to 82 marks in 5th exam
so, average marks obtained by Sunita = sum of marks of all exams / number of exams .
= ( 87 + 92 + 94 + 95 + x)/5
= ( 368 + x)/5
now, a/c to question,
Sunita wants to obtain grade A for that average marks should be greater than 90 or equal to 90.
e.g. (368+x)/5 ≥ 90
368 + x ≥ 90×5 = 450
368 + x ≥ 450
x ≥ 82
hence, Sunita Should got greater than or equal to 82 marks in 5th exam
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