Graph-Third Quartle

Question

Find the third quartile class and frequency of the class from the given graph. How many students are there above the class? My attempt : Here, $N=120$. Third quartile lies in $\frac {3N}{4}$item. $$=90 item$$ So, $Q_3 class = 20-30$.

but I couldn't do that second part of the question. Please help. Thanks

Answer 1

Here, You have got the $Q_3$ class as $(20-30)$.

Upper limit of the class touches the less than curve at $100$

Lower limit of the class touches the less than curve at $80$. So, frequency of the class $=100-80=20$.

Also, Corresponding frequency of upper limit of the third quartile class in the more than curve is $20$. So, the number of students above the class is $20$.

.....))