GATE CSE 2021 Set 1 | GA Question: 1

Question

​​​​​​The ratio of boys to girls in a class is $7$ to $3$.

Among the options below, an acceptable value for the total number of students in the class is:

• A. $21$
• B. $37$
• C. $50$
• D. $73$

Comments

We have 7:3 ration, If we check using the options,

(a) 21 – we can’t divide this number in 7:3 ration.

(b) 37 – even 37 also we can’t divide in 7:3 ratio.

(c) 50 – If we divide 35+15 = 50 we get ratio of 7:3.

(d) 73 – we can’t divide in 7:3 ratio.

Answer → (c)

Answer 1

Option C.

The number of boys is a multiple of $7$ i.e., $7M,$ for some integer $M.$

The number of girls is a multiple of $3$ i.e., $3M.$ 

$\therefore$ The total number of students $= 7M + 3M = 10M,$ i.e., a multiple of $10.$

Only option that fits is C.

Comments

BOYS ARE IN MULTIPLE OF 7 AND GIRLS ARE IN MULTIPLE OF 3 SO TOTAL IT SHOULD BE IN MULTIPLE OF 10.