Quantitative Aptitude - Arithmetic Ability Questions

Q:

If July 9th,2013 falls on Sunday then Jan 7th,2014 falls on which day?

A) Sunday B) Saturday
C) Monday D) Friday
 
Answer & Explanation Answer: A) Sunday

Explanation:

 

First,we count the number of odd days for the left over days in the given period.Here,given period is 09-07-2013 to 07-01-2014

Month Jul Aug Sep Oct Nov Dec Jan
Days 22 31 30 31 30 31 7
Odd Days 1 3 2 3 2 3 0

 Therefore, No. of Odd Days =  1 + 3 + 2 + 3 + 2 + 3 + 0 = 14 = 0 odd days

So, given day Sunday + 0 = Saturday is the required result.

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Filed Under: Calendar

86 16437
Q:

The average age of a group of persons going for picnic is 16 years. Twenty new persons with an average age of 15 years join the group on the spot due to which their average age becomes 15.5 years. The number of persons initially going for picnic is :

A) 15 B) 20
C) 23 D) 24
 
Answer & Explanation Answer: B) 20

Explanation:

Let the initial number of persons be x. Then,

16x + 20 * 15 = 15.5 (x + 20) <=> 0.5x = 10 <=> x = 20.

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Filed Under: Average

19 16430
Q:

How many cubes of 10cm edge can be put in a cubical box of 1m edge

A) 10 B) 100
C) 1000 D) 10000
 
Answer & Explanation Answer: C) 1000

Explanation:

Number of cubes= (100x100x100) / (10x10x10)= 1000

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Filed Under: Volume and Surface Area
Exam Prep: Bank Exams
Job Role: Bank PO

45 16428
Q:

A person goes to his office at 1/3rd of the speed at which he returns from his office. If the average speed during the whole trip is 12 m /h . what is the speed of the person while he was going to his office?

A) 10 B) 6
C) 8 D) can't be determined
 
Answer & Explanation Answer: C) 8

Explanation:

u = k , v= 3k 

 

2uvu+v 2×k×3kk+3k=12  => k = 8km/h

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Filed Under: Time and Distance

12 16423
Q:

Suppose 7 students are staying in a hall in a hostel and they are allotted 7 beds. Among them, Parvin does not want a bed next to Anju because Anju snores. Then, in how many ways can you allot the beds?

A) 2400 B) 6400
C) 3600 D) 7200
 
Answer & Explanation Answer: C) 3600

Explanation:

Let the beds be numbered 1 to 7.

 

Case 1 : Suppose Anju is allotted bed number 1. 

Then, Parvin cannot be allotted bed number 2. 

So Parvin can be allotted a bed in 5 ways. 

After alloting a bed to Parvin, the remaining 5 students can be allotted beds in 5! ways.

So, in this case the beds can be allotted in 5´5!ways = 600 ways.

 

Case 2 : Anju is allotted bed number 7. 

Then, Parvin cannot be allotted bed number 6 

As in Case 1, the beds can be allotted in 600 ways.

 

Case 3 : Anju is allotted one of the beds numbered 2,3,4,5 or 6. 

Parvin cannot be allotted the beds on the right hand side and left hand side of Anju’s bed. For example, if Anju is allotted bed number 2, beds numbered 1 or 3 cannot be allotted to Parvin.

Therefore, Parvin can be allotted a bed in 4 ways in all these cases.

After allotting a bed to Parvin, the other 5 can be allotted a bed in 5! ways.

Therefore, in each of these cases, the beds can be allotted in 4´ 5! = 480 ways. 

The beds can be allotted in (2x 600 + 5 x 480)ways = (1200 + 2400)ways = 3600 ways

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15 16414
Q:

A box contains 100 balls, numbered from 1 to 100. If three balls are selected at random and with replacement from the box, what is the probability that the sum of the three numbers on the balls selected from the box will be odd?

A) 1/6 B) 1/3
C) 1/2 D) 1/4
 
Answer & Explanation Answer: C) 1/2

Explanation:

P(odd) = P (even) =12 1(because there are 50 odd and 50 even numbers)

 

Sum or the three numbers can be odd only under the following 4 scenarios:

 

Odd + Odd + Odd = 12*12*1218

 

Odd + Even + Even = 12*12*12=18

 

Even + Odd + Even = 12*12*12=18

 

Even + Even + Odd = 12*12*12 = 18

 

Other combinations of odd and even will give even numbers. 

 

Adding up the 4 scenarios above:

 

1818+1818 = 48 = 12

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Filed Under: Probability

10 16385
Q:

The number of ways that 8 beads of different colours be strung as a necklace is 

A) 2520 B) 2880
C) 4320 D) 5040
 
Answer & Explanation Answer: A) 2520

Explanation:

The number of ways of arranging n beads in a necklace is (n-1)!2=(8-1)!2=7!2 = 2520 

(since n = 8)

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Filed Under: Permutations and Combinations
Exam Prep: AIEEE , Bank Exams , CAT
Job Role: Bank Clerk , Bank PO

27 16375
Q:

The marked price of an article is increased  by 25% and the selling price is increased by 16.66%, then the amount of profit doubles. If the original marked price  be Rs. 400 which is greater than the corresponding cost price by 33.33% , what is the increased selling price?

A) 240 B) 360
C) 420 D) 600
 
Answer & Explanation Answer: C) 420

Explanation:

Initially                 CP           profit            SP                MP

 

                              100           x               (100+x)         133.33

 

After Change     100           2x             (100+x)   

 

Now,   Since (100+x)  - 100 = 2x

 

           76 x= 20%

 

                         CP            Profit              SP             MP

 

                        100             20               120           133.33

 

So,                  300             60               360             400

 

Again             300            120              420

 

So the increased selling price = Rs. 420

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Filed Under: Profit and Loss

62 16370