5
Q:

In a village the average age of n people is 42 years. But after the verification it was found that the age of a person had been  considered 20 years less than the actual age, so the new average, after the correction,increased by 1. The value of n is :

A) 21 B) 20
C) 22 D) None of these

Answer:   B) 20



Explanation:

It is the same as a person with 20 years more age  replaces an existing person of the group ( or village)

Since the total age of the village having n persons, is being increased by 20 years and the average age of village is being increased by 1 year, hence there are total 20 people in the village.

 

Alternatively :  ( n x 42 ) + 20 = ( n x 43 )

                          => n=20

Q:

Third proportion of 10 and 20 is

A) 30 B) 40
C) 25 D) 20
 
Answer & Explanation Answer: B) 40

Explanation:

The third proportional of two numbers p and q is defined to be that number r such that

p : q = q : r.

 

Here, required third proportional of 10 & 20, and let it be 'a'

=> 10 : 20 = 20 : a

10a = 20 x 20

=> a = 40

 

Hence, third proportional of 10 & 20 is 40.

Report Error

View Answer Workspace Report Error Discuss

3 340
Q:

The average weight of 45 passengers in a bus is 52 kg. 5 of them whose average weight is 48 kg leave the bus and other 5 passengers whose average weight is 54 kg join the bus at the same stop. What is the new average weight of the bus?   

A) 54.21 kgs B) 51.07 kgs
C) 52.66 kgs D) 53.45 kgs
 
Answer & Explanation Answer: C) 52.66 kgs

Explanation:

Given total number of passengers in the bus = 45

First average weight of 45 passengers = 52 kgs

Average weight of 5 passengers who leave bus = 48

Average weight of passengers who joined the bus = 54

Therefore, the net average weight of the bus is given by

= 45 x 52 - 5 x 48 + 5 x 5445 = 237045= 1583= 52.66 kgs.

Report Error

View Answer Workspace Report Error Discuss

15 1201
Q:

12 boys decided to constribute Rs. 750 each to an Orphange. Suddenly few of them boys dropped out and consequently the rest had to pay Rs. 150 more. Then the number of boys who dropped out?

A) 4 B) 6
C) 2 D) 3
 
Answer & Explanation Answer: C) 2

Explanation:

Total money decided to contribute = 750 x 12 = 9000

Let 'b' boys dropped

The rest paid 150/- more

=> (12 - b) x 900 = 9000

=> b = 2

Hence, the number of boys who dropped out is 2.

Report Error

View Answer Workspace Report Error Discuss

14 1380
Q:

P, Q, R, S, T and U are six consecutive odd numbers and their average is 52. What is the product of P and U ?

A) 2212 B) 2154
C) 2349 D) 2679
 
Answer & Explanation Answer: D) 2679

Explanation:

Let x, x+2, x+4, x+6, x+8 and x+10 are six consecutive odd numbers.

Given that their average is 52

Then, x + x+2 + x+4 + x+6 + x+8 + x+10 = 52×6

6x + 30 = 312

x = 47

So Product = 47 × 57 = 2679

Report Error

View Answer Workspace Report Error Discuss

13 1414
Q:

19 friends went to a restaurant for a combined weekend dinner party. 13 of them spent Rs. 79 each on their dinner and the rest spent Rs. 4 more than the average expenditure of all the 19. What was the total money spent by them?   

A) Rs. 1398.96 B) Rs. 1457.09
C) Rs. 1662.35 D) Rs. 1536.07
 
Answer & Explanation Answer: D) Rs. 1536.07

Explanation:

Let average expenditure was Rs. R

13 x 79 + 6x(R + 4) = 19R

=> R = Rs. 80.84

Total money = 19 x 80.84 = Rs. 1536.07.

Report Error

View Answer Workspace Report Error Discuss

19 1287
Q:

The average age of a class is 19 years. While the average age of girls is 18 and that of boys is 21. If the number of girls in the class is 16, Find the number of Boys in the class?

A) 12 B) 10
C) 8 D) 6
 
Answer & Explanation Answer: C) 8

Explanation:

Let the number of boys = x

From the given data,

=> [21x + 16(18)]/(x+16) = 19

=> 21x - 19x = 19(16) - 16(18)

=> 2x = 16

=> x = 8

Therefore, the number of boys in the class = 8.

Report Error

View Answer Workspace Report Error Discuss

13 1484
Q:

The mean of 100 observations is 40. It is found that an observation 84 was misread as 48. Then the correct mean is ?

A) 40.36 B) 41.24
C) 41.92 D) 42.05
 
Answer & Explanation Answer: A) 40.36

Explanation:

Given,

mean of 100 observations is 40

=> Total of 100 observations = 40 x 100 = 4000

84 is misread as 48

=> Difference = 84 - 48 = 36

=> Now, new total of 100 observations = 4000 + 36 = 4036

Correct Mean = 4036/100 = 40.36

Report Error

View Answer Workspace Report Error Discuss

16 1815
Q:

The average marks of a student in 7 subjects is 85. His average marks in 6 subjects except English is 83. What is his marks in English ?

A) 97 B) 98
C) 92 D) 93
 
Answer & Explanation Answer: A) 97

Explanation:

Marks in English  = 85×7 – 83×6

= 595 – 498

= 97

Report Error

View Answer Workspace Report Error Discuss

18 1860