# TCS Papers: Sample Questions 63 - 65 of 502

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## Question number: 63

» Aptitude

### Write in Short

What is an operating system?

### Explanation

The operating system is the most important program that on a computer. Every general-purpose computer must have an operating system to run other programs and applications. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending to the display screen, keeping track of files and on the, and controlling peripheral devices such as disk drives and. The operating system is also responsible for security, ensuring that unauthorized users do not access the system.

## Question number: 64

» Aptitude

### Write in Short

There are 150 weights. Some are 1 kg weights and some are 2 kg weights. The sum of the weights is 260. What is the number of 1kg weights?

### Explanation

- There are total 150 weights. Some of them are 1 kg and some of them are 2 kg.
- Let there be x number of 1 kg and 150 – x number of 2 kg. Sum of weights is 260. Writing the given information in equation form,

- The number of 1 kg weights is 40.

## Question number: 65

» Aptitude

### Write in Short

A number is selected at random from the number 1,2, …, 50. What is the probability that the number is multiple of either 6 or 9?

### Explanation

Let the event A is getting multiples of 6, and the event B is getting multiples of 9.

A = {6,12,18, …. . 48} = 8

So, P (A)

B = {9,18, ………. . 45} = 5

So, P (B)

But events A and B have some common points 18,36.

So, A∩B = 2

P (A∩B)

From union probability formula

So, probability of getting multiple of 6 or 9 is .