​Find the ratio at which salt of Rs.17,00 per kg should be mixed with salt of Rs.20,00 per kg to produce salt of Rs.18,40 per kg.

Correct option is B

Given:

Salt of Rs.17,00 per kg should be mixed with salt of Rs.20,00 per kg to produce salt of Rs.18,40 per kg.

Formula used:

​$$\frac{\text{Amount of Solution 1}}{ \text{Amount of Solution 2}} = \frac{C_2 - C_m}{C_m - C_1} \\$$​​

Where: 
$$C_1$$​ is the concentration of Solution 1
$$C_2$$​ is the concentration of Solution 2
$$C_m$$​is the concentration of the resulting mixture

Solution:

Here,

$$C_1$$ =  Rs. 1700per kg

​$$C_2 = \text{Rs. } 2000 \text{ per kg} \\$$​​

​$$C_m = \text{Rs. } 1840 \text{ per kg} \\$$​​
​$$\frac{\text{Amount of Solution 1}}{ \text{Amount of Solution 2}} = \frac{C_2 - C_m}{C_m - C_1} \\$$​​
​​Put the values in formula,​

​$$\frac{\text{Amount of Solution 1}}{\text{Amount of Solution 2}} = \frac{2000 - 1840 }{1840 - 1700}$$​​
$$\frac{\text{Amount of Solution 1}}{\text{Amount of Solution 2}} = \frac{160 }{140}$$ = $$\frac{8}{7}$$​​

Amount of Solution 1 : Amount of Solution 2

8:7

Thus, option (b) is correct.

Alternative Method:

160:140

8:7