ADDMATH past year 2015

Who know how to solve this question?
Although i got answer,but i dont understand the answer.
Q22 and Q24
Q24 question in next post.thank you

1 Like

22 Table 22 shows the number of students by gender in two different rooms. The number
of male students in room Wira is not stated.

Jadual 22 menunjukkan bilangan murid mengikut jantina dalam dua bilik berbeza. Bilangan
murid lelaki di dalam bilik Wira tidak dinyatakan.

A student is chosen at random from each room. Find the number of male student in room Wira, if the probability that both students chosen are of different gender is 7/12

Seorang murid dipilih secara rawak dari setiap bilik.
Cari bilangan murid lelaki dalam bilik Wira, jika keharangkalian kedua-dua murid yang dipilih
itu adalah berbeza jantina ialah 7/12.

Answer/ Jawapan: