GATE Questions

Q:

If x = 2 + 223 + 213 then find the value of x3-6x2+6x ?

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

Explanation:

Given that x = 2+ 223 + 213

 

So x - 2 = 223 + 213

 

Now cubing on both sides, we get

 

 

=> x3-8-6x2+12x = 4 + 2 + 6(x-2)

 

Therefore, x3-6x2+6x = -6 + 8 = 2

 

 

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Filed Under: Square Roots and Cube Roots
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Q:

A man covers a distance of 1200 km in 70 days resting 9 hours a day, if he rests 10 hours a day and walks with speed 1½ times of the previous in how many days will he cover 840 km ?

A) 39 days B) 37 days
C) 35 days D) 33 days
 
Answer & Explanation Answer: C) 35 days

Explanation:

Distance d = 1200km
let S be the speed

he walks 15 hours a day(i.e 24 - 9)
so totally he walks for 70 x 15 = 1050hrs.

S = 1200/1050 => 120/105 = 24/21 => 8/7kmph


given 1 1/2 of previous speed
so 3/2 * 8/7= 24/14 = 12/7

New speed = 12/7kmph

Now he rests 10 hrs a day that means he walks 14 hrs a day.

time = 840 x 7 /12 => 490 hrs
=> 490/14 = 35 days

So he will take 35 days to cover 840 km.

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Filed Under: Time and Distance
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19 11901
Q:

A simple interest earned on certain amount is triple the money when invested for 16 years.what is the interest rate offered ?

A) 13.33 % B) 14.25 %
C) 16.98 % D) 18.75 %
 
Answer & Explanation Answer: D) 18.75 %

Explanation:

Given,
S.I = 3 Principal Amount
=> 3A = A x 16 x R/100
By solving, we get
=> R = 18.75%

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Filed Under: Simple Interest
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7 4446
Q:

When I was married 10 years ago my wife is the 6th member of the family. Today my father died and a baby born to me.The average age of my family during my marriage is same as today. What is the age of Father when he died ?

A) 50 yrs B) 60 yrs
C) 70 yrs D) 65 yrs
 
Answer & Explanation Answer: B) 60 yrs

Explanation:

Let the Father be x years when he died

Average Age 10 years ago be A

Total Age 10 years ago = 6*A

Total Age after 10 years(Just before father's Death) = 6A + 6*10 = 6A + 60

Father Died and Baby was born => the Total number of people in the family is Same (6)
Baby born today so age of baby = 0

(6A +60 - x)/6 = 6A/6
=> A + 10 -(x/6) = A
=> x/6 = 10
=> x = 60

Therefore we can conclude that the father was 60 years old when he died.

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Filed Under: Problems on Ages
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56 19265
Q:

Out of sixty students, there are 14 who are taking Economics and 29 who are taking Calculus. What is the probability that a randomly chosen student from this group is taking only the Calculus class ?

A) 8/15 B) 7/15
C) 1/15 D) 4/15
 
Answer & Explanation Answer: B) 7/15

Explanation:

Given total students in the class = 60
Students who are taking Economics = 24 and
Students who are taking Calculus = 32
Students who are taking both subjects = 60-(24 + 32) = 60 - 56 = 4
Students who are taking calculus only = 32 - 4 = 28
probability that a randomly chosen student from this group is taking only the Calculus class = 28/60 = 7/15.

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Filed Under: Probability
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12 4483
Q:

A batsman scores 26 runs and increases his average from 14 to 15. Find the runs to be made if he wants top increasing the average to 19 in the same match ?

A) 74 B) 79
C) 72 D) 60
 
Answer & Explanation Answer: A) 74

Explanation:

Number of runs scored more to increse the ratio by 1 is 26 - 14 = 12
To raise the average by one (from 14 to 15), he scored 12 more than the existing average.
Therefore, to raise the average by five (from 14 to 19), he should score 12 x 5 = 60 more than the existing average. Thus he should score 14 + 60 = 74.

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Filed Under: Average
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9 6889
Q:

One girl can eat 112 chocolates in half a minute, and her boy friend can eat half as many in twice the length of time. How many chocolates can both boy and girl eat in 12 seconds ?

A) 44 B) 32
C) 56 D) 49
 
Answer & Explanation Answer: C) 56

Explanation:

Girl eats 112 chocolates in 30 sec

so she can eat in 12 sec is 12 x 112/30 = 44.8 chocolates.

 

Her boy friend can eat one-half of 112 in twice of 30 sec

so he can eat 56 in 60 sec


Then he can eat in 12 sec is 56 x 12/60 = 11.2 chocolates.

 

Hence, together they can eat = 44.8 + 11.2 =56 chocolates in 12 seconds.

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Filed Under: Time and Work
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7 2862
Q:

A class consists of both boys and girls along with a teacher. After a class, the teacher drinks 9 litres of water, a boy drinks 7 litres of water and a girl drinks 4 litres of water. If after a class 42 litres of water was consumed, find the number of girls in the class ?

A) 8 B) 6
C) 5 D) 3
 
Answer & Explanation Answer: D) 3

Explanation:

Given teacher drinks 9 ltr
Let number of boys be 'A'.
Let number of girls be 'B'.
Boy drinks 7 ltr and girl drinks 4 ltr
After class total water consumed = 42 ltr
Then,
9 + 7A + 4B = 42
=> 7A + 4B = 33
By trial and error method,
The only integers which satisfy the equation is A = 3 and B = 3
Therefore, number of girls in the class = 3.

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Filed Under: Simplification
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