Question

In four schools $B_1, B_2, B_3, B_4$ the percentage of girls students is $12, 20, 13, 17$ respectively. From a school selected at random, one student is picked up at random and it is found that the student is a girl. The probability that the school selected is $B_2$, is

• A. $\frac{6}{31}$
• B. $\frac{10}{31}$
• C. $\frac{13}{62}$
• D. $\frac{17}{62}$

Answer 1

Answer: (B)

$\frac{10}{31}$

Answer 2

Total no. of students in four schools $= 12 + 20 + 13 + 17 = 62.$ Now, one student is selected at random. $\therefore$ Total outcomes $= 62_{C_1}$ No. of ways to select a student from $B_2 = 20_{C_1}$ $\therefore$ Required probability $=\frac{20_{C_1}}{62_{C_1}}=\frac{20}{62}=\frac{10}{31}$