alligation and mixtures mcq pdf Model Questions & Answers, Practice Test for ibps rrb so officer sclae 2 3 single exam 2024

Answer: (a)

Here, alligation is applicable for 'money per boy or girl".

Mean value of money per student = $3900/65$ = 60P

∴ Boys : Girls = 3 : 2

∴ Number of boys = $65/{3 + 2}$ × 3 = 39

and number of girls = 65 - 39 = 26

Answer: (d)

Let cost of 1 litre milk be Rs. 1.

Mlk in 1 litre mix. in B = $8/13$ litre, C.P. of a litre mix. in B = Rs.$5/7$

Milk in 1 litre mix. in B = $5/7$ litre, C.P. of 1 litre mix. in B = Rs. $5/7$

Milk in 1 litre of final mix. = $(900/13 × 1/100 × 1) = 9/13$ litre;

mean price = Rs. $9/13$

By the rule of alligation, we have:

C.P. of 1 litre mixture in A & B below in Figure

∴ Required ratio = $2/91 : 1/13$ = 2 : 7

Answer: (a)

In order to sell at a 25% profit by selling at 13.75 the cost price should be 13.75/1.25 = 11.

Also since water is freely available, we can say that the ratio of water and soda must be 1: 11.

Answer: (b)

or, (75 : 30) × $1/3 (56 : 14) × 1/2 (28 : 7 ) × 1/7$

25 : 10

25 : 7

4 : 1

57 : 18 = 75

% of water in mixture

= $18/75 × 100 = 24%$