Quantitative Aptitude - Arithmetic Ability Questions

Q:

On multiplying a number by 7, the product is a number each of whose digits is 3. The smallest such number is  ?

A) 476190476 B) 48617
C) 47619 D) 4587962
 
Answer & Explanation Answer: C) 47619

Explanation:

By hit and trail, we find that

47619 x 7 = 333333.

7) 333333 (47619
    333333
----------------
        0

And 476190476 x 7 = 3333333333 but smallest number is 47619.

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Filed Under: Problems on Numbers
Exam Prep: AIEEE , Bank Exams , CAT , GATE
Job Role: Bank Clerk , Bank PO

16 13706
Q:

The average of six numbers is x and the average of three of these is y. If the average of the remaining three is z, then :

A) x = y + z B) 2x = y + z
C) 3x = 2y - 2z D) none of these
 
Answer & Explanation Answer: B) 2x = y + z

Explanation:

Clearly, we  have : x = (3y + 3z ) / 6 or 2x = y + z.

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Filed Under: Average

13 13703
Q:

A number X is chosen at random from the numbers -3, -2, -1, 0, 1, 2, 3. What is the probability that |X|<2

A) 3/7 B) 3/4
C) 4/5 D) 5/7
 
Answer & Explanation Answer: A) 3/7

Explanation:

X can take 7 values.
To get |X|+2) take X={−1,0,1}

=> P(|X|<2) = Favourable CasesTotal Cases = 3/7

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Filed Under: Probability

31 13692
Q:

What is the rate of simple interest?
I. The total interest earned was Rs. 4000.
II. The sum was invested for 4 years.

A) I alone sufficient while II alone not sufficient to answer B) II alone sufficient while I alone not sufficient to answer
C) Either I or II alone sufficient to answer D) Both I and II are not sufficient to answer
 
Answer & Explanation Answer: D) Both I and II are not sufficient to answer

Explanation:

We know that, R = (100 x S.I) / (P x T)

Now I gives, S.I = Rs. 4000.

        II gives,  T = 4 years.

But, P is unknown. So, we cannot find R.

So, given data is insufficient to get R.

 

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Filed Under: Simple Interest
Exam Prep: Bank Exams
Job Role: Bank PO

3 13665
Q:

P, Q, and R can do a job in 12 days together.  If their efficiency of working be in the ratio 3 : 8 : 5, Find in what time Q can complete the same work alone?

A) 36 days B) 30 days
C) 24 days D) 22 days
 
Answer & Explanation Answer: A) 36 days

Explanation:

Given the ratio of efficiencies of P, Q & R are 3 : 8 : 5

Let the efficiencies of P, Q & R be 3x, 8x and 5x respectively

They can do work for 12 days.

=> Total work = 12 x 16x = 192x

 

Now, the required time taken by Q to complete the job alone = 162x8x = 24 days.

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17 13658
Q:

A piece of ribbon 4 yards long is used to make bows requiring 15 inches of ribbon for each. What is the maximum number of bows that can be made?

A) 8 B) 9
C) 10 D) 11
 
Answer & Explanation Answer: B) 9

Explanation:

The maximum number of bows will be 4 yards (= 4 x 36 inches) divided by 15 inches.

This gives 9.6. But as a fraction of a bow is no use, we can only make 9 bows.

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Filed Under: Numbers
Exam Prep: GRE

22 13652
Q:

A box contains 2 white balls, 3 black balls and 4 red balls. In how many ways can 3 balls be drawn from the box, if at least one black ball is to be included in the draw?

A) 48 B) 64
C) 63 D) 45
 
Answer & Explanation Answer: B) 64

Explanation:

We may have(1 black and 2 non-black) or (2 black and 1 non-black) or (3 black).

 

Required number of ways=3C1*6C2+3C2*6C1+3C3 = (45 + 18 + 1) =64

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5 13648
Q:

Find the next number in the series 3, 4, 5, 5, 12, 13, 7, 24, 25, 8, 15, ...

A) 26 B) 16
C) 17 D) 18
 
Answer & Explanation Answer: C) 17

Explanation:

The pattern is 32+42=52,  52+122=13272+242=252 

The next number = 82+152=172

 i.e. 17

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Filed Under: Numbers
Exam Prep: CAT , Bank Exams
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27 13611