GATE Questions

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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7 8066
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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15 8061
Q:

The average age of a couple and their son was 40 years, the son got married and a child was born just two years after their marriage. When child turned to 10 years, then the average age of the family becomes 38 years. What was the age of the daughter in law at the time of marriage ?

A) 12 years B) 10 years
C) 14 years D) 13 years
 
Answer & Explanation Answer: A) 12 years

Explanation:

Given the average age of couple and their son = 40

=> Sum of age (H +W +S) = 40×3

Let the age of daughter in law at the time of marriage = D years

Now after 10 years,

(H + S +W) + 3×12 + D +12 + 10 = 38×5

178 + D = 190

D = 190 -178 = 12 years

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Filed Under: Problems on Ages
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13 8058
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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5 8054
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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6 8041
Q:

Microwave communication uses high-frequency.

A) TRUE B) FALSE
Answer & Explanation Answer: A) TRUE

Explanation:

Microwaves are high-frequency signals in the 300 MHz to 300 GHz range. This is in contrast to radio signals, which are typically broadcast in all directions. Radio signals operate in the 3 Hz to 300 MHz range.


Microwave signals are used for both satellite and ground-based communications.

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Subject: Physics
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5 8038
Q:

The ratio of present ages of X and Y is 4:5. Which of the following can't be the ratio of ages of X and Y, 20 years ago ?

A) 2 : 5 B) 8 : 15
C) 9 : 10 D) 3 : 5
 
Answer & Explanation Answer: C) 9 : 10

Explanation:

The ratio of X and Y ages at present is 4:5. 

Then, the ratio 20 years ago will not be more than the ratio at present.

So, from the options 9:10 is not satifying => its ratio is 0.9 which is greater than presnt ratio of 0.8.

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8 8014
Q:

Vishal, Priyatham, Raghu, Karthik and Veeru are five friends. Vishal is twice as old as priyatham. Raghu is half age of Priyatham. Vishal is half the age of Veeru and Raghu is twice the age of Karthik.

Question:
Who is the youngest ?

A) Veeru B) Karthik
C) Vishal D) Raghu
 
Answer & Explanation Answer: B) Karthik

Explanation:

Let Priyatham's age = x

Then, Vishal's age = 2x; Raghu's age = x/2; Veeru's age = 4x ; Karthik's age = x/4

So, the descending order of ages is :

Veeru > Vishal > Priyatham > Raghu > Karthik

Therefore,  Karthik is the youngest.

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14 8010