GATE CS 2018
Question 1 |
What is the missing number in the following sequence?
2, 12, 60, 240, 720, 1440, .... 0
2880 | |
1440 | |
720 | |
0 |
Discuss it
Question 1 Explanation:
The series starts with 2.
We multiply first term with 6 to get second term 12
Then we multiply second term with 5 to get third term 60
Then we multiply third term with 4 to get fourth term 340
Then we multiply fourth term with 3 to get fifth term 720
Then we multiply fifth term with 2 to get fifth term 1440.
Then we need to multiply with 1 and we get 1440 again.
Question 2 |
What would be the smallest natural number which when divided either by 20 or by 42 or by 76 leaves a remainder ‘7’ in each case is_
3047 | |
6047 | |
7987 | |
63847 |
Discuss it
Question 2 Explanation:
We need a number that can be written as 20x + 7, 42y + 7, 76z + 7 for three integers x, y and z.
We basically need to find least common multiple of 20 (2 * 2 *5), 42(2 * 3 * 7) and 76(2 * 2 * 19) which is
2 * 2 * 5 * 3 * 7 * 19 = 20 * 21 * 19 = 420 * 19 = 7980
So our number is 7980 + 7 = 7987.
Note - You can also verify options using virtual calculator.
Question 3 |
"From where are they bringing their books? _________ bringing _________ books from _________."
The words that best fill the blanks in the above sentence are
Their, they're, there | |
They're, their, there | |
There, their, they're | |
They're, there,there |
Discuss it
Question 3 Explanation:
"From where are they bringing their books? Who bringing Whose books from Where."
Who - A group as subject = They are
Whose - of that group = their
Where - from a place = there
"From where are they bringing their books? They are bringing their books from there."
So, option (B) is correct choice.
Question 4 |
A __________ investigation can sometimes yield new facts, but typically organized once are more successful.
Meandering | |
Timely | |
Consistent | |
Systematic |
Discuss it
Question 4 Explanation:
Meandering (as adjective) = proceeding in a convoluted or undirected fashion.
Timely (as adjective) = done or occurring at a favourable or useful time; opportune.
Consistent (as adjective) = acting or done in the same way over time, especially so as to be fair or accurate.
Systematic (as adjective) = done or acting according to a fixed plan or system; methodical.
Therefore, meandering is correct choice, all other options are similar to the word organized.
Question 5 |
What is the area of the circle which has the diagonal of the square as its diameter if the area of square is ' d ' ?
πd | |
πd2 | |
(1/4) πd2 | |
(1/2)πd |
Discuss it
Question 5 Explanation:
One important observation to solve
the question :
Diagonal of Square = Diameter of Circle.
Let side of square be x.
From Pythagoras theorem.
Diagonal = √(2*x*x)
We know area of square = x * x = d
Diameter = Diagonal = √(2*d)
Radius = √(d/2)
Area of circle = π * √(d/2) * √(d/2) = 1/2 * π * d
Question 6 |
In the figure below, ∠DEC+∠BFC is equal to _______ .
∠ BCD - ∠ BAD | |
∠ BAD + ∠ BCF | |
∠ BAD + ∠ BCD | |
∠ CBA + ∠ ADC |
Discuss it
Question 6 Explanation:
Option (A) is correct.
Question 7 |
In a party, 60% of the invited guests are male and 40% are female. If 80% of the invited guests attended the party and if all the invited female guests attended, what would be the ratio of males to females among the attendees in the party?
2:3 | |
1:1 | |
3:2 | |
2:1 |
Discuss it
Question 7 Explanation:
Let total males and females be 60x and
40x respectively.
Total number of people = (60x + 40x)
Total number of people who attended :
0.8(60x + 40x) = 80x
Let y males attended. It is given all
1females attended
40x + y = 80x
y = 40x which is same as females.
Alternative Approach -
Lets total number of people = 100.
Therefore, 60 are male and and 40 are female.
But total 80 guests are attended and all 40 female attended the party.
So, there remaining (80 - 40 = 40) attendees should be male.
Then the ration of male to female among attendees is 40 : 40 = 1 : 1
Question 8 |
A six sided unbiased die with four green faces and two red faces is rolled seven times. Which of the following combinations is the most likely outcome of the experiment?
Three green faces and four red faces. | |
Four green faces and three red faces. | |
Five green faces and two red faces. | |
Six green faces and one red face |
Discuss it
Question 8 Explanation:
Considering uniformly distributed outcomes, we get 4 greens and 2 reds in six throws. Then in one more throw, green is more likely.
So, option (C) is correct.
Question 9 |
If pqr ≠ 0 and p^(-x) = 1/q, q^(-y) = 1/r, r^(-z) = 1/p, find the value of the product xyz ?
-1 | |
1 / pqr | |
1 | |
pqr |
Discuss it
Question 9 Explanation:
Taking logs of given three values, we get
1/q = p-x -------(1)
1/r = q-y -------(2)
1/p = r-z -------(3)
1/q = p-x
= r-xz [Putting value of p from (3)]
= q-xyz [Putting value of r from (2)]
= 1 / qxyz
On comparing power of q both sides, we get xyz = 1
So, option (C) is correct.
Question 10 |
In appreciative of social improvement completed in a town, a wealthy philanthropist decided to give gift of Rs. 750 to each male senior citizen and Rs. 1000 for female senior citizens. There are total 300 citizens and the 8/9th of total men and 2/3rd of total women claimed the gift. What is amount of money philanthropist paid?
15000 | |
200000 | |
115000 | |
151000 |
Discuss it
Question 10 Explanation:
Let there be x total men.
Total amount paid = x * 750 * 8/9 + (300 - x)*1000*2/3
= x*2000/3 + 300*1000*2/3 - x*2000/3
= 200000
There are 66 questions to complete.
