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 Quantitative Aptitude - Arithmetic Ability Questions

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Q:

A fair coin is tossed 11 times. What is the probability that only the first two tosses will yield heads ?

A) (1/2)^11 B) (9)(1/2)
C) (11C2)(1/2)^9 D) (1/2)
 
Answer & Explanation Answer: A) (1/2)^11

Explanation:

Probability of occurrence of an event, 

P(E) = Number of favorable outcomes/Numeber of possible outcomes = n(E)/n(S)


⇒ Probability of getting head in one coin = ½, 

⇒ Probability of not getting head in one coin = 1- ½ = ½, 

Hence, 

All the 11 tosses are independent of each other.

∴ Required probability of getting only 2 times heads =122×129=1211

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Filed Under: Probability
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7 8105
Q:

Ayush was born two years after his father's marriage. His mother is five years younger than his father but 20 years older than Ayush who is 10 years old. At what age did the father get married ?

A) 25 years B) 24 years
C) 23 years D) 22 years
 
Answer & Explanation Answer: C) 23 years

Explanation:

Ayush's present age = 10 years.
His mother's present age = (10 + 20) years = 30 years.
Ayush's father's present age = (30 + 5) years = 35 years.
Ayush's father's age at the time of Ayush's birth = (35 - 10) years = 25 years.

Therefore Ayush's father's age at the time of marriage = (25 - 2) years = 23 years.

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Filed Under: Problems on Ages
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11 8104
Q:

If Reena’s age was twice of her present age, when subtracted from four times three years from hence, with three times the three years before her present age. What will be her age after one year ?

A) 22 yrs B) 21 yrs
C) 20 yrs D) 24 yrs
 
Answer & Explanation Answer: A) 22 yrs

Explanation:

Let Reena’s present age be 'K' yrs.
Given:{(K+3) x 4} - {(K-3) x 3)}
=> K = 21 yrs
So her present age is 21 yrs.
Then, her age after 1 year is 22 yrs.

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Filed Under: Problems on Ages
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6 8102
Q:

It costs Rs. p each to send the first thousand messsages and Rs. q to send each subsequent one . If r is greater than 1,000, how many Rupees will it cost to send r messages ?

A) 1000 (r - p) + pq B) 1000 p + qr
C) 1000 (r - q) + pr D) 1000(p - q) + qr
 
Answer & Explanation Answer: D) 1000(p - q) + qr

Explanation:

We need to find the total cost to send r messsages, r > 1000.

The first 1000 messsages will cost Rs.p each (Or) 

The total cost of first 1000 messsages = Rs.1000p

The remaining (r - 1000) messsages will cost Rs.q each (Or)

The cost of the (r - 1000) = Rs.(r - 1000)y

 

Therefore, total cost = 1000p + rq - 1000q

= 1000(p - q) + qr

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Filed Under: Average
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15 8097
Q:

Tom's father is thrice as old as Tom. 10 years ago Tom's father's age was 7 times his age. What is Tom's current age? 

 

 

A) 17 years  B) 16 years 
C) 15 years  D) 14 years
 
Answer & Explanation Answer: D) 14 years

Explanation:
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Filed Under: Problems on Ages
Exam Prep: Bank Exams

24 8096
Q:

An individual deposited 20% of 25% of 30% of what he had into his account with a bank. If he deposited Rs.750, how much was he having initially with him before depositing ?

A) Rs. 38000 B) Rs. 47000
C) Rs. 50000 D) Rs. 35000
 
Answer & Explanation Answer: C) Rs. 50000

Explanation:

Let 'x' be the amount he had in the bank.

=> 20/100(25/100(30/100(x))) = 750

x = 750 x 8000/120 = Rs. 50000

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Filed Under: Percentage
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5 8091
Q:

Three triangles are marked out of a bigger triangle at the three vertices such that each side of each of the smaller triangles is one-third as long as each corresponding side of the bigger triangle. The ratio of the area of the three small triangles taken together to that of the rest of the bigger triangle is ?

A) 1:2 B) 1:3
C) 3:1 D) 1:9
 
Answer & Explanation Answer: A) 1:2

Explanation:
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Filed Under: Ratios and Proportions
Exam Prep: Bank Exams

10 8082
Q:

What would be the least number of years in which the simple interest on Rs.2600 at % will be an exact number of rupees ?

A) 2 B) 3
C) 4 D) 5
 
Answer & Explanation Answer: B) 3

Explanation:

 S.I=Rs.2600*203*1100*t

 S.I=Rs.5203*t

 t=3

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Filed Under: Compound Interest
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6 8077