Quantitative Aptitude - Arithmetic Ability Questions

Q:

7 years ago, the ratio of the ages of Anirudh to that of Bhavana, was 7:9. Chandhu is 12 years older than Anirudh and 12 years younger than Bhavana. What is Chandhu's present age?

A) 91 years B) 115 years
C) 103 years D) Can't be determined
 
Answer & Explanation Answer: C) 103 years

Explanation:

Let present Anirudh's age be 'A' and Bhavana's age be 'B'

Given seven years, their ratio is 7:9

=> A-7 : B-7 = 7 : 9

=> 9A - 7B = 14 .......(1)

And given,

Chandhu is 12 years older than A nad 12 years younger than B

=> C = A + 12....(2)

=> B = C + 12

=> B = A + 12 + 12 .....(From (2))

=> B = A + 24 ....(3)

Put (3) in (1)

9A - 7(A+24) = 14

9A - 7A - 168 = 14

2A = 182

=> A = 91 years

=> C = A + 12 = 91 +12 = 103 years.

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Filed Under: Problems on Ages
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Q:

Two trains start from same place at same time at right angles to each other. Their speeds are 36km/hr and 48km/hr respectively. After 30 seconds the distance between them will be ?

A) 900 mts B) 300 mts
C) 250 mts D) 500 mts
 
Answer & Explanation Answer: D) 500 mts

Explanation:

Using pythagarous theorem,
distance travelled by first train = 36x5/18x30 = 300m
distance travelled by second train = 48x5/18x30 = 400m
so distance between them =√( 90000 + 160000) = √250000 = 500mts.

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Filed Under: Time and Distance
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Q:

Out of the five integral numbers C is the average of A and D.  B is greater than C and less than D.Also B is the average of A and E . The middle most number in the sequence 

A) A B) B
C) C D) D
 
Answer & Explanation Answer: B) B

Explanation:

     D _  C  _ A          --------(1)

     D > B > C           --------(2)

from (1) and (2)

     D > B > C > A   ---------(3)

 

Again      E _ B _ A

But B > A, from (3)

So          E > D > B > C > A      [ Since B is the average of E and A so it is eqidistant from both E and A]

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Filed Under: Average

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Q:

If the sum of two numbers is 55 and the H.C.F. and L.C.M. of these numbers are 5 and 120 respectively, then the sum of the reciprocals of the numbers is equal to ?

A) 13/125 B) 14/57
C) 11/120 D) 16/41
 
Answer & Explanation Answer: C) 11/120

Explanation:

Let the numbers be a and b.
We know that product of two numbers = Product of their HCF and LCM
Then, a + b = 55 and ab = 5 x 120 = 600.
=> The required sum = (1/a) + (1/b) = (a+b)/ab
=55/600 = 11/120

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Filed Under: HCF and LCM
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Q:

What is the difference between the biggest and the smallest fraction among 2/3 , 3/4 , 4/5 and 5/6?

A) 1/6 B) 1/12
C) 1/20 D) 1/30
 
Answer & Explanation Answer: A) 1/6

Explanation:

Converting each of the given fractions into decimal form, we get

2/3 = 0.66, 3/4 = 0.75, 4/5 = 0.8, 5/6 = 0.833 

Since 0.833>0.8>0.75>0.66 

So, 5/6 > 4/5 > 3/4 > 2/3 

Therefore,  Required Difference = 5/6 - 2/3 = 1/6

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Filed Under: Decimal Fractions

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Q:

The Value of  logtan10+logtan20++logtan890 is

A) -1 B) 0
C) 1/2 D) 1
 
Answer & Explanation Answer: B) 0

Explanation:

= log tan10+log tan890 + log tan20+ log tan880++log tan450  

 

= log [tan10 × tan890] + log [tan20 × tan880 ] ++log1  

 

 tan(90-θ)=cotθ and tan 450=1  

 

= log 1 + log 1 +.....+log 1 

 

= 0.

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Filed Under: Logarithms
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Q:

In a public bathroom there are n taps 1,2,3...n. Tap1 and Tap2 take equal time to fill the tank while Tap3 takes half the time taken by Tap2 and Tap4 takes half the time taken by Tap3. Similarly each next number of tap takes half the time taken by previous number of Tap i.e, K-th Tap takes half the time taken by (K-1)th Tap. If the 10th tap takes 2 hours to fill the tank alone then what is the ratio of  efficiency of 8th tap and 12th tap, respectively?

A) 4:1 B) 5:3
C) 16:1 D) 1:16
 
Answer & Explanation Answer: D) 1:16

Explanation:

Time taken by 8th tap = 2 x 2 x 2= 8 hours

Time taken by 12th tap = 2x (1/2) x (1/2)  = 1/2 hour

Ratio of time taken by 8th tap and 12th tap = 8 : 1/2 =16:1

Therefore, Ratio of efficiencies of 8th tap and 12th tap =1:16

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Filed Under: Time and Work

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Q:

There are 5 multiple choice questions in an examination. How many sequences of answers are possible, if the first three questions have 4 choices each and the next two have 6 choices each?

A) 1112 B) 2304
C) 1224 D) 2426
 
Answer & Explanation Answer: B) 2304

Explanation:

Number of questions = 5
Possibilities of choices for each question 1 to 5 respectively = 4, 4, 4, 6, 6


Reuired total number of sequences

= 4 x 4 x 4 x 6 x 6

= 2304.

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Filed Under: Permutations and Combinations
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