CyberChallenge.IT 2020

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CyberChallenge.IT 2020 - Test

Demo of the test for the 2020 edition of CyberChallenge.IT

Additional material for other tests is available at the link https://cyberchallenge.it/training

Note: the expression pow(x, y) indicates x to the power of y.

Question 1

Which is the unit digit of the least common multiple between 4834 and 5135?

1 point

Clear selection

Question 2

What is the correct negation of this proposition? “For all green animals, it is true that if the green animal is also a frog, the animal likes water.”

1 point

Water is not green

All green animals that do not like water are not frogs

There is a green animal that is a frog but does not like water

There is a frog that does not like water

Clear selection

Question 3

Henry starts with a list of the first 1000 positive integers. At each step he performes the following operations:

- Erase all the non-positive integers, if any.

- Erase all the integers with repeated digits (e.g. 111, 121, 122), if any.

- Decrements every remaining number by 1.

After how many steps all the numbers will be erased?

1 point

100

101

Clear selection

Question 4

Consider the following function:

Which assignment of (a,b,c) makes f(a,b,c) equal to 3?

1 point

(false, false, true)

(true, false, false)

(false, true, false)

(false, false, false)

Clear selection

Question 5

Consider the following function:

What does x(3,3) return?

1 point

Clear selection

Question 6

Consider the following statements:

- If Danny owns a computer also Mark owns a computer

- If Mark owns a computer, then also Steve owns a computer

Which of the following sentences are true if Danny owns a computer?

(a) Mark owns a computer

(b) Steve owns a computer

1 point

a and b

Only b

Only c

Only a

Clear selection

Question 7

Consider the following functions:

What does x(100) return?

1 point

Clear selection

Question 8

Consider the following incomplete code fragment:

What condition should replace $1 to make the code correct?

1 point

(i + j) % 2 == 1

0 <= (abs(2 - i) + abs(2 - j)) <= 2

-2 <= (i + j - 4) <= 2

2 <= (i + j) <= 6

Clear selection

Question 9

Let x, y and z be real numbers. Consider the following equations:

x + y + z = 20

x + 2y + 3z = 16

What is the value of x + 3y + 5z?

1 point

Clear selection

Question 10

100 boxes are placed in a row. We know that exactly one of them contains a diamond. Each box is labelled with “The diamond is either in the right box or in the left box”.

This is true for only one box.

How many boxes do we need to open to be sure to know where the diamond is?

1 point

Clear selection

Question 11

The numbers a,b,c,d are 1,2,2,3 in some order. What is the greatest possible value of pow(a, pow(b, pow(c, d))) (a to the b-th power to the c-th power to the d-th power)?

1 point

256

729

512

Clear selection

Question 12

You have 10 balls, 2 for each of 5 colours. The 2 balls of a certain colour weight exactly 1 gram more than the others, that have exactly the same weight, but you do not know the colour.

You are given a scale with two pans and a digital display that gives the signed differences between the two pans.

You can put whatever number of balls on each pan.

How many weighs do you need to determine the colour of the two different balls?

1 point

Clear selection

Question 13

Consider the following statements:

- Those who like programming like reversing

- Those who like guessing like forensics

Those who do not like forensics do not like programming

Which of the following sentences are true?

(a) Those who like guessing like reversing

(b) Those who like programming like forensics

(d) Those who like guessing do not like programming

(e) Those who like programming like guessing

1 point

b and c

They are all false

Only b

a and d

Clear selection

Question 14

On an island there are 2020 people, each of them are truth-tellers or liars. At a party, more than 2000 of them came and sat around a big circular table.

During the dinner, each of them said that his two neighbours are of different types (one truth-teller and one liar).

What is the maximum number of truth-tellers in the island?

1 point

1346

1347

1353

Clear selection

Question 15

Consider the following function, where ^ and & are bitwise XOR and bitwise AND operations.

What operation is equivalent to the function f?

1 point

x + y

x * y

x - y

None of the others

Clear selection

Submit

Clear form

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