I, II and III
I and II
II and III
I and III
Correct answer is A
No explanation has been provided for this answer.
4
3
1
2
Correct answer is B
Range = 18 - 15
= 3
378 ways
462 ways
840 ways
924 ways
Correct answer is A
\(^{3}C_{1} \times ^{9}C_{5}=\frac{3!}{(3-1)!1!}\times \frac{9!}{(9-5)!5!}\\=\frac{3!}{2!1!}\times \frac{9!}{4!5!}\\=\frac{3 \times 2!}{2!\times 1}\times \frac{9\times8\times7\times6\times5!}{4\times3\times2\times1\times5!}\\=3\times9\times2\times7\\=378 \hspace{1mm}ways\)
9/35
11/35
4/7
3/7
Correct answer is C
Gold medals = 30
silver medals = 22
Bronze medals = 18/70
P(Gold medals) = 30/70 = 3/7
∴ P(not Gold medal) = 1 - 3/7
= 4/7
9
7
42
15
Correct answer is A
Let the number of students = x
Total age of the students = 15x
Total age including age of the teacher = 15x + 45
Mean of their ages; (15x + 45)/(x + 1) = 18
15x + 45 = 18(x + 1)
15x + 45 = 18x + 18
18x - 15x = 45 - 18
3x = 27
x = 9