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The average of 20 numbers is 14. If each number is multiplied by 24, then the average of the new set of numbers is

A.

38

B.

14

C.

24

D.

336

Answer with explanation

Answer: Option DExplanation

when each of the 20 numbers is multiplied by 24, the average will also be raised to 24 times

so the new avg :- 24 x 14 = 336

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Sujata scored 2240 marks in an examination that is 128 marks more than the minimum passing percentage of 64%. What is the percentage of marks obtained by Meena if she scores 907 marks less than Sujata?

A.

35

B.

40

C.

45

D.

30

Answer with explanation

Answer: Option BExplanation

If x be the total marks then,

x * (64/100) = 2240 – 128 = 2112

Or, x = 2112 * (100/64) = 3300

Marks obtained by Meena = 2240 – 907 = 1333

So, the percentage of marks obtained by Meena = (1333/3300) * 100 = 40.39% ≈ 40%

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Of the three numbers, second is twice the first and is also thrice the third. If the average of the three numbers is 44, the largest number is

A.

24

B.

36

C.

72

D.

108

Answer with explanation

Answer: Option CExplanation

Let the first number be 3x. Second number is 6x. Third number is 2x.

So average = (2x + 3x + 6x)/3 = 11x/3

But 11x/3 = 44

So, x = 12

6x = 72

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The average expenditure of a man for the first five months is Rs. 1200 and for the next seven months is Rs. 1300. Find his monthly average income if he saves Rs. 2900 during the year ?

A.

Rs. 1500

B.

Rs. 1475

C.

RS. 1450

D.

Rs. 1425

Answer with explanation

Answer: Option AExplanation

Let his monthly salary be x rupees.

So, 5 (x – 1200) + 7 (x-1300) = 2900

12x – 6000 – 9100 = 2900

So, x = 18000/12 = 1500

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10 years ago, the average age of a family of 4 members was 24 years. Two children having been born (with age difference of 2 years), the present average age of the family is the same. The present age of the youngest child is :

A.

4

B.

3

C.

2

D.

1

Answer with explanation

Answer: Option BExplanation

Total age of 4 members, 10 years ago = (24 x 4) years = 96 years.

Total age of 4 members now = [96 + (10 x 4)] years = 136 years.

Total age of 6 members now = (24 x 6) years = 144 years.

Sum of the ages of 2 children = (144 – 136) years = 8 years.

Let the age of the younger child be x years.

Then, age of the elder child = (x+2) years.

So, x+(x+2) =8 <=> x=3

Age of younger child = 3 years.

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Distance between two stations A and B is 778km. A train covers the journey from A to B at 84km per hour and returns back to A with a uniform speed of 56km per hour. Find the average speed of train during the whole journey.

A.

67.2 km/hr

B.

60 km/hr

C.

57 km/hr

D.

30.5 km/hr

Answer with explanation

Answer: Option AExplanation

Average speed =[2xy /(x+y)]km/hr.

=[(2*84*56) /(84+56)] km/hr.

=[(2*84*56)/140] km/hr.

= 67.2km/hr.

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The average of the marks of 12 students in a class is 36. If the marks of each student are doubled, find the new average?

A.

79

B.

72

C.

49

D.

37

Answer with explanation

Answer: Option BExplanation

Sum of the marks for the 12 students = 12 * 36 = 432. The marks of each student are doubled, the sum also will be doubled.

The new sum = 432 * 2 = 864. So, the new average = 864/12 = 72.

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The average income of A, B and C is Rs. 12,000 per month and average income of B, C and D is Rs. 15,000 per month. If the average salary of D be twice that of A, then the average salary of B and C is in Rs. :

A.

18,000

B.

13,500.

C.

9,000

D.

8,000

Answer with explanation

Answer: Option BExplanation

A+B+C = 12000*3

B+C+D = 15000*3

→ D-A = 3000*3 = 9000

Also, D = 2A

Then, D = 18000 and A = 9000

Therefore,

Average salary of B and C,

= (45000-18000)/2 = 13,500.

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Find the average of first 97 natural numbers.

A.

48

B.

49

C.

37

D.

47

Answer with explanation

Answer: Option BExplanation

*1st Method:*

Average of 1st n natural number is given by = ([n*(n+1)]/2)/n

Average of 1st 97 natural number is given by = {([97*(97+1)]/2)/97} = 49

*2nd Method:*

These numbers are in AP series, so average,

= (sum of corresponding term)/2

= (1+97)/2 = 49

Or, (2+96)/2 = 49

Or, (3+95)/2 = 49 And so on.

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The average price of 10 books is Rs. 12 while the average price of 8 of these books is Rs. 11.75. Of the remaining two books, if the price of one book is 60% more than the price of the other, what is the pice of each of these two books?

A.

16,12

B.

23,9

C.

8,7

D.

10,16

Answer with explanation

Answer: Option DExplanation

Total pice of the two books = Rs. [(12 x 10) – (11.75 x 8)]

= Rs. (120 – 94) = Rs. 26.

let the price of one book be Rs. x

Then, the price of other book = Rs. (x + 60% of x) = Rs.(x+(3/5)x) = Rs. (8/5)x

So, x+(8/5)x =26 <=> x =10

The prices of the two books are Rs. 10 and Rs. 16

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A.

66 kg

B.

67 kg

C.

68 kg

D.

69 kg

Answer with explanation

Answer: Option BExplanation

Let Arun’s weight by X kg.

According to Arun, 65 < X < 72

According to Arun’s brother, 60 < X < 70.

According to Arun’s mother, X <= 68

The values satisfying all the above conditions are 66, 67 and 68.

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The average weight of 25 boys in a class is 48 kgs. The average weight of the class of 40 students is 45 kgs. What is the average weight of the 15 girls in the class?

A.

42.5 kg

B.

44 kgs

C.

40 kgs

D.

42 kgs

Answer with explanation

Answer: Option CExplanation

Total weight of boys in the class = 25 *48 = 1200 kgs

Total weight of all students in the class = 45 * 40 = 1800 kgs

Total weight of the girls in the class = 1800 – 1200 = 600 kgs

Average weight of girls = = 40 kgs

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Average of 10 matches is 32, How many runs one should score to increase his average by 4 runs

A.

72

B.

80

C.

76

D.

70

Answer with explanation

Answer: Option CExplanation

Average after 11 innings should be 36

So, Required score = (11 * 36) – (10 * 32)

= 396 – 320 = 76

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