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A Learning Portal from Recruitment India

The average of 20 students is 12 years, if the teacher’s age is included, average increases by one. The age of the teacher is

A.

30 years

B.

33 years

C.

35 years

D.

28 years

Answer with explanation

Answer: Option BExplanation

Solution:

Average of 20 students = 12 years

Total age of 20 students

= 20 × 12

= 240 years

When teacher included average become 13 years

Now, total age 20 students and teacher

= 13 × 21 = 273 years

∴ Age of teacher

= 273 – 240

= 33 years

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Of the four numbers, whose average is 60, the first is one-fourth of the sum of the last three. The second number is one-third of the sum of other three, and the third is half of the other three. Find the fourth number.

A.

60

B.

80

C.

48

D.

52

Answer with explanation

Answer: Option DExplanation

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If the average income of a family of ‘x’ members is Rs. 25000 while average income of another family of 6 members is Rs. 32000, then find the value of ‘x’ if the average income of both families is Rs. 28000

A.

6

B.

7

C.

8

D.

9

Answer with explanation

Answer: Option CExplanation

Avg income of 1st family=25

Avg income of 2nd family=32

Both the families=28

1st family=28-25=3

2nd family=32-28=4

Requied ratio=4:3

Ratio of number of family members of 1^{st}to 2^{nd}is 4 : 3. In the second family, there are 6 members, hence in the 1^{st}family there are 8 members, only then the ratio = 8 : 6 or 4 : 3 hence x = 8.

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The average age of a group of 10 students was 18. The average age increased by 1 years when two new students joined the group. What is the average age of the two new students who joined the group?

A.

23.5

B.

23

C.

24

D.

24.5

Answer with explanation

Answer: Option CExplanation

The average age of a group of 10 students is 18.

Therefore, the sum of the ages of all 10 of them = 10 * 18 = 180

When two students joins the group, the average increase by 1. New Average = 19

Now there are 12 students Therefore, sum of all the ages of 12 students = 12 X 19 = 228

Therefore, the sum of the ages of two students who joined = 228 – 180 = 48

And the average age of these two students = 24

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Marks of a student were wrongly entered in computer as 83, actual marks of that student were 63. Due to this mistake average marks of whole class got increased by half (1/2). Find the total number of students in that class?

A.

40

B.

45

C.

35

D.

30

Answer with explanation

Answer: Option AExplanation

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A.

28 kmph

B.

24 kmph

C.

16 kmph

D.

14 kmph

Answer with explanation

Answer: Option BExplanation

Distance between home and Bank – x km

Total distance = x + x = 2x

Total time taken = x/60 + (x/2)/10 + (x/2)/30

= x/12

Average speed = 2x/(x/12) = 24 kmph

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The average cost 32 different Mobiles is Rs. 9000. Among them, Oppo which is the costliest is 70% higher price than the cheapest Mobile Lava. Excluding those both mobiles, the average of the Mobiles is Rs.8880. Then what is the cost of Oppo Mobile?

A.

Rs. 10000

B.

Rs. 11600

C.

Rs. 12400

D.

Rs.13600

Answer with explanation

Answer: Option DExplanation

L+O = 21600

O = L*170/100

O = 13600

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The average value of property of Mittal, Ambani and Singhania is Rs.11111 crore. The property of Singhania is as less than the property of Mittal is greater than the average property of both the Singhania and Mittal. The value of property of Ambani is :

A.

Rs.111 crore

B.

Rs. 1111 crore

C.

Rs. 11111 crore

D.

can’t be determined

Answer with explanation

Answer: Option CExplanation

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The average salary of a person for the months of January, February, March and April is Rs.8000 and that for the months February, March, April and May is Rs.8500. If his salary for the month of May is Rs.6500, find his salary for the month of January?

A.

3000

B.

2500

C.

4500

D.

5000

Answer with explanation

Answer: Option CExplanation

Sum of the salaries of the person for the months of January, February, March and April = 4 * 8000 = 32000 —-(1)

Sum of the salaries of the person for the months of February, March, April and May = 4 * 8500 = 34000 —-(2)

(2)-(1) i.e. May – Jan = 2000

Salary of May is Rs.6500

Salary of January = Rs.4500

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In a family of 8, the men eat on average 72kg of food and women eat on an average 50kg of food. The men and women are equal in number. A hungry woman named Neetu joined the family for dinner and the average consumption became 67.How much did Neetu eat (in kgs)?

A.

Rs. 85

B.

Rs. 80

C.

Rs. 90

D.

Rs. 115

Answer with explanation

Answer: Option DExplanation

As men and women are equal so , there are 4 women and 4 men so, total consumption will be 72×4 = 288(by men) and 50×4 = 200(by women)

Total consumption = 488.

But after including Neetu the average consumption for 9 people is given to be 67.So the total consumption will be 67×9 = 603. So, Neetu’s consumption will be = 603 – 488 = 115

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A grocer has a sale of Rs. 6435, Rs. 6927, Rs. 6855, Rs. 7230 and Rs. 6562 for 5 consecutive months. How much sale must he have in the sixth month so that he gets an average sale of Rs. 6500?

A.

Rs. 4991

B.

Rs. 5991

C.

Rs. 6001

D.

Rs. 6991

Answer with explanation

Answer: Option AExplanation

Total sale for 5 months = Rs. (6435 + 6927 + 6855 + 7230 + 6562) = Rs. 34009.

Required sale = Rs. [ (6500 x 6) – 34009 ]

= Rs. (39000 – 34009)

= Rs. 4991.

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The average salary per head of the entire staff of an office including the officers and clerks is Rs.90. The average salary per head of the officers is Rs.600 and that of the clerk is Rs.84. If the number of officers is 12, find the number of clerks in the office?

A.

1540

B.

960

C.

840

D.

1020

Answer with explanation

Answer: Option DExplanation

Let number of clerk be x.

Average salary of entire staff = Rs. 90

Average salary of per head officer = Rs. 600

Number of head officers = 12

Total salary of 12 officer = 600 * 12 = Rs. 7200

Average salary of clerk = Rs. 84

Total salary of clerk = x * 84

12 + x (90) = 7200 + 84x

1080 + 90x = 7200 + 84x

6x = 6120

x = 1020

Hence, Number of clerks in the office = 1020.

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A library has an average of 510 visitors on Sundays and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is :

A.

285

B.

290

C.

297

D.

305

Answer with explanation

Answer: Option AExplanation

Since the month begins with a Sunday,

so there will be five Sundays in the month,

Required average = (510 * 5 + 240 * 25) / 30

8550/30 = 285.

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In an exam, the average marks for 80 students of Class V is 35. The average of marks in section A of the class is 55 while the average of marks in section B is 30. Find the number of students in section B?

A.

45

B.

50

C.

64

D.

60

Answer with explanation

Answer: Option CExplanation

Total students i.e. Section A + Section B = 80

Section A = (80 – Section B) = 80 – B

∴ 80 x 35 = B x 30 + (80 – B) x 55

2800 = 30B + 4400 – 55B

1600 = 25 B

B = 64

∴ B = 64 = Number of students in section B.

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A.

66 kg.

B.

67 kg.

C.

69 kg.

D.

68 kg.

Answer with explanation

Answer: Option BExplanation

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The batting average for 40 innings of a cricket player is 50 runs. His highest score exceeds his lowest score by 172 runs. If these two innings are excluded, the average of the remaining 38 innings is 48 runs. The highest score of the player is ?

A.

165

B.

170

C.

172

D.

174

Answer with explanation

Answer: Option DExplanation

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A.

23 years

B.

24 years

C.

25 years

D.

None of these

Answer with explanation

Answer: Option AExplanation

Let the average age of the whole team by x years.

11x – (26 + 29) = 9(x -1)

11x – 9x = 46

2x = 46

x = 23.

So, average age of the team is 23 years.

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If we choose four numbers, the average of the first three will be 16 and that of last three is 15. If the last number is 18, the first number will be?

A.

20

B.

21

C.

23

D.

25

Answer with explanation

Answer: Option BExplanation

Sum of Last 3 numbers= 15*3=45

Hence the last number is 18

So, Sum of 2nd & 3rd = 45-18= 27

Again sum of first three numbers =16*3=48

Therefore the 1st number will be

sum of 1st 3 number-sum of 2nd & 3rd number

i.e. 48-27=21

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Rakshit sold 21 tables in a day. He told his father, “My earnings at end of the day are Rs 400000/-. The average earning from the first 11 tables I sold was Rs 20000/-“. What were his average earnings from the remaining tables?

A.

Rs. 9125

B.

Rs. 9750

C.

Rs. 16,363

D.

Rs. 18,000

Answer with explanation

Answer: Option DExplanation

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The average weight of 8 person’s increases by 2.5 kg when a new person comes in place of one of them weighing 65 kg. What might be the weight of the new person?

A.

76 kg

B.

76.5 kg

C.

85 kg

D.

Data inadequate

Answer with explanation

Answer: Option CExplanation

Total weight increased = (8 x 2.5) kg = 20 kg.

Weight of new person = (65 + 20) kg = 85 kg.

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If the average of 20 numbers is zero, how many numbers may be greater than zero?

A.

49

B.

50

C.

19

D.

25

Answer with explanation

Answer: Option CExplanation

Average of 20 numbers = 0.

Sum of 20 numbers = (0 x 20) = 0.

So, it is quite possible that 19 of these numbers may be positive and if their sum is “X” then 20th number will be (-X).

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A grocer has a sale of Rs 6435, Rs. 6927, Rs. 6855, Rs. 7230 and Rs. 6562 for 5 consecutive months. How much sale must he have in the sixth month so that he gets an average sale of Rs 6500?

A.

4991

B.

5467

C.

5987

D.

6453

Answer with explanation

Answer: Option AExplanation

Total sale for 5 months = Rs. (6435 + 6927 + 6855 + 7230 + 6562) = Rs. 34009.

Required sale = Rs.[(6500 x 6) – 34009] = Rs. (39000 – 34009) = Rs. 4991.

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A.

35

B.

65

C.

88

D.

25

Answer with explanation

Answer: Option DExplanation

39x = 5 + 12 + 15 + 19 + (x – 4)44

x = 25

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A car owner buys petrol at Euro 7.50, Euro 8 and Euro 8.50 per litre for three successive years. What approximately is the average cost per litre of petrol if he spends Euro 4000 each year?

A.

Euro 7.98

B.

Euro 8

C.

Euro 8.50

D.

Euro 9

Answer with explanation

Answer: Option AExplanation

Total quantity of petrol consumed in 3 years =(4000/7.50+4000/8+4000/8.50)liters

= 4000(2/15+1/8+2/17) liters

= 76700/51 liters

Total amount spent = Rs. (3 x 4000) = Rs. 12000.

Average cost = Rs. (12000*51/76700) = Rs. 7.98.

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