Question

the ratio of number of boys and girls is 4:3. If there are 18 girls in a class, find the number of boys in the class and the total number of students in the class.​

Answer 1

Step-by-step explanation:

4/3=x/18

x=24

means the number if boys are 24

Answer 2

ɢɪᴠᴇɴ :

• total volume of mixture is 45 litres
• ratio of suger and salt is 1 : 2

ᴛᴏ ғɪɴᴅ :

• the amont of sugar solution to be added if the ratio has to be 2 : 1

sᴏʟᴜᴛɪᴏɴ :

Number of litres of sugar solution in the mixture

$= ( \frac{1}{(1 + 2)} ) \times 45$

$= \frac{1}{ \cancel3} \times \cancel{45}$

$\sf = 15 \: litres$

So, 45 - 15 = 30 litres of salt solution is present in it.

Let the quantity of sugar solution to be added be x litres.

Setting up the proportion,

sugar solution / salt solution = (15+x)/30 = 2/1 → x = 45.

$\sf \leadsto \frac{sugar \: solution}{salt \: solution} \to \frac{(15 + x)}{30} = \frac{2}{1}$

$\sf \to15 + x = 2 \times 30$

$\sf \to \: x = 60 - 15$

$\sf \to \: x = 45$

Therefore, 45 litres of sugar solution has to be added to bring it to the ratio 2:1.