26
Q:

# The average age of students of a class is 15.8 years. The average age of boys in the class is 16.4 years and that of the girls is 15.4 years, The ratio of the number of boys to the number of girls in the class is :

 A) 1 : 2 B) 2 : 3 C) 3 : 4 D) 4 : 5

Explanation:

Let the ratio be k : 1. Then,

k * 16.4 + 1 * 15.4 = (k + 1) * 15.8

<=> (16.4 - 15.8) k = (15.8 - 15.4)  <=> k =  0.4/0.6 = 2/3.

Required ratio  = 2/3 : 1 = 2 : 3.

Q:

After replacing an old member by a new member, it was found that the average age of five members of a club is the same as it was 3 years ago. The difference between the ages of the replaced and the new members?

 A) 16 years B) 15 years C) 14 years D) 13 years

Explanation:

Let avg ages of 5 members at present is G

And age of new member is m and an older is n

Required = (5G + m - n)/5 = G - 3

m - n = 15 years

3 249
Q:

A student's average marks in five subjects is 82. If the average marks of first two subject is 86.5 and the average marks of last two subjects is 84. Find the marks of third subject?

 A) 69 B) 67 C) 71 D) 73

Explanation:

The total marks of all 5 subjects = 82 x 5 = 410

Total marks of 1st two subjects = 86.5 x 2 = 173

Total marks of last two subjects = 84 x 2 = 168

Now, marks in 3rd subject = 410 - (173 + 168) = 410 - 341 = 69.

11 265
Q:

Find the average of first 50 natural numbers?

 A) 25 B) 25.5 C) 26 D) 26.5

Explanation:

We Know that sum of the n natural numbers =$n(n+1)2$

Then sum of 50 natural numbers= $50(51)2$= 1250

Average of the 50 natural numbers = $125050$ = 25.5

11 504
Q:

The average score of boys in an examination in a school is 81 and that of the girls is 83 and the average score of the school is 81.8. Then what will be ratio between the number of girls to the number of boys, in the examination?

 A) 3:2 B) 2:3 C) 4:3 D) 3:4

Explanation:

Let the number of boys = b

Let the number of girls = g

From the given data,

81b + 83g = 81.8(b + g)

81.8b - 81b = 83g - 81.8g

0.8b = 1.2g

b/g = 1.2/0.8 = 12/8 = 3/2

=> g : b = 2 : 3

Hence, ratio between the number of girls to the number of boys = 2 : 3.

16 1108
Q:

Out of three numbers, the first is twice the second and is half of the third. If the average of the three numbers is 56, what will be the sum of the highest number and the lowest number?

 A) 120 B) 160 C) 80 D) 60

Explanation:

Let the three numbers be x, y, z.

From the gien data,

x = 2y ....(1)

x = z/2 => z = 2(2y) = 4y .....(From 1)  ...........(2)

Given average of three numbers = 56

Then,

Now,

x = 2y => x = 2 x 24 = 48

z = 4y = 4 x 24 = 96

Now, the highest number is z = 96 & smallest number is y = 24

Hence, required sum of highest number and smallest number

= z + y

= 96 + 24

= 120.

10 1355
Q:

How many window coverings are necessary to span 50 windows, if each window covering is 15 windows long?

 A) 4 B) 15 C) 3 D) 50

Explanation:

Given that,

Number of windows = 50

Each window covering covers 15 windows

=> 50 windows requires 50/15 window coverings

= 50/15 = 3.333

Hence, more than 3 window coverings are required. In the options 4 is more than 3.

Hence, 4 window coverings are required to cover 50 windows of each covering covers 15 windows.

6 5112
Q:

Ian has 14 boxes of paper and divides them evenly between 4 coworkers. How many whole boxes did each coworker get?

 A) 2 B) 2.5 C) 3 D) 3.5

Explanation:

Given number of boxes = 14

Number of workers = 4

Now, number of whole boxes per worker = 14/4 = 3.5

Hence, number of whole boxes per each coworker = 3

9 9775
Q:

Five boxes of bananas sell for Rs. 30. how many boxes can you buy for Rs.9?

 A) 2 B) 1.5 C) 1.25 D) 2.5

Explanation:

Given Five boxes of bananas sell for Rs. 30.

=> 1 Box of Bananas for = 30/5 = Rs. 6

Then, for Rs. 9

=> 9/6 = 3/2 = 1.5

Hence, for Rs. 9, 1.5 box of bananas can buy.