The following scores were obtained in a statistics exam
class interval[50,60)[60,70)[70,80)[80,90)[90,100)Class value xi 5565758595Frequency fi14652
Find:
i) Considering the class value, the average score of the whole class.
ii) The ratio of the no. of students who scored above 80 to the ratio no. of students who scored below 70.
76.667, 7:5
i) Average score of the whole class = 1×55+4×65+6×75+5×85+2×951+4+6+5+2
= 138018= 76.667
ii) No. of students above 80= no. of students in the range [80,90) + no. of students in the range [90,100) = 5 + 2 = 7 – (1)
No. of students below 70= no. of students in the range [50,60) + no. of students in the range [60,70) = 1 + 4 = 5 – (2)
Ratio of the no. of students above 80 to the ratio no. of students below 70 = (1):(2) = 7:5