There are 40 students in a classroom, 9/20 of them are boys and 4/5 of them are right-handed. How many right-handed boys are there in the classroom?
(a) Between 10 and 32.
(b) Between 14 and 32.
(c) Between 10 and 18.
(d) Between 14 and 18.
(e) Between 18 and 36.
There are (9/20 x 40 = 18) boys in the class.
80% of them are right-handed, means that (4/5 x 18 = 14.4).
Answer C is the best answer.