# Day-7 | Aptitude Questions and Answers with Explanation

Total number of boys and girls in a class is A. The total number of girls subtracted from the total number of boys is B. Now please express the portion of girls to the total strength in terms of ‘A’ and ‘B’.

[/tab] [tab]**Answer:**

Let x denote the number of boys. Let y denote the number of girls.

A = x+y->equation 1

B = x-y-> equation 2

Subtracting equation 2 from equation 1 we will get y = (AB)/2 -> equation 3

Ratio of total number of girls to the total strength will be y / x+y.

Now substitutingAforx + y as per equation 1 and (A- B)/2 for y as per equation 3 we will get the answer as (A – B) / (2A)

[/tab][/tabs] [divider] [tabs type=”horizontal”] [tabs_head][tab_title]Question-2[/tab_title][tab_title]Explanation[/tab_title][/tabs_head] [tab]Indra and Chandra together have Rs.12740. If ½ of what Indra has is equivalent to 1/ 5 of what Chandra has, What is the amount Chandra is having?

a) 3640 b)9100 c) 1820 d) 5400

[/tab] [tab]**Answer:**

b) 9100

½ of Indra’s amount = * 1 / 5 *of Chandra’s amount

Indra’s amount = *115 *X *2/1 *= *2/5 *of Chandra’s amount Indra’s amount: Chandra’s amount = 2: 5

Therefore, Indra’s amount will be *2/7 *of Rs.12740 and Chandra’s amount will be *5/7 *of Rs.12740 Hence, Chandra has *12740×5/7 *= Rs.9100

A telecom communication college claims an average test pass rate of76.8%. What is the least number of students required to achieve this result?

a)249 b)125 c)62 d)373

[/tab] [tab]**Answer:**

b) 125

For such questions, it is advisable to go by options rather than trying to solve directly.

Essentially the questions is, if theoretically 76.8 students out of 100 pass (theoretical because, practically the number of students cannot be fraction like 76.8), what could be a minimum total number of students required so that the number of passing students is not a fraction but a whole number.

Starting by the smallest of the options, if we assume 62 is the total number of students, the number of students who pas,s = (76.8/100) X 62 = 47.6. This cannot be real as 47.6 is a fraction .

If we assume 125 as the total number of students, the number of students who pass = (76.8/100) X 125 = 96, which is perfectly possible as 96 is a whole number. Hence 125 is the answer.

For ,achieving 76.8% being a full number, minimum number that is required is 125. 96 passes out of 125 gives an average of 76.8%

[/tab][/tabs] [divider] [tabs type=”horizontal”] [tabs_head][tab_title]Question-4[/tab_title][tab_title]Explanation[/tab_title][/tabs_head] [tab]A group of students from Netherlands visited Chennai to study about the various aspects of life prevalent in Chennai. They also studied about the weather forecasts. The average temperature of days from Sunday to Wednesday was 36 degrees and that of from Monday to Thursday was 33.5 degrees, The temperature on Thursday wa,s 2/3 of Sunday. What was the temperature on Sunday?

a)20 b)30 c)40 d)38

[/tab] [tab]**Answer:**

b) 30 degrees

Average Temperature from Sunday to Wednesday – 36°. Total temperature from

Sunday to Wednesday – 36 x 4 = 144 deg.

Average temperature from Monday to Thursday – 33.5 deg.

Total temperature from Monday to Thursday – 33.5 x 4 = 134

If the total temperature from Monday to Wednesday be K Then, Sunday’s temperature + K = 144 -> eq 1 Thursday’s temperature + K = 134 -> eq 2

It is stated that Thursday temperature,was 2/3 of Sunday. Applying this to eq 2, we get:

2/3 (Sunday’s Temperature) + K = 134 -> eq 3

Eq 1 – Eq 3 => 1/3 (Sunday’s Temperature) = 10. Therefore, Sunday temperature = 30 deg.

[/tab][/tabs] [divider] [tabs type=”horizontal”] [tabs_head][tab_title]Question-5[/tab_title][tab_title]Explanation[/tab_title][/tabs_head] [tab]A prominent School in Chennai had classes from LKG to XII standard. A study was made about the marks scored by students of XII in a government examination. The average marks of 60 students in a class was 45. The average marks of the boys in the class is 40 and the average marks of the girls in the class is 50. What is the ratio between the number of boys and girls in the class?

a)1:1 b)2: 1 c) 3: 1 d) none of these

[/tab] [tab]**Answer: **

a) 1 : 1

Total marks of 60 students = 60 x 45 = 2700 Suppose number of girls = x

Number of boys = (60 – x)

Number of girls X average marks of girls

[/tab][/tabs]