ST Microelectronics Papers: Sample Questions 1 - 3 of 40

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Question number: 1

» Aptitude

Short Answer Question▾

Write in Short

What are the gates used in half adder.

Explanation

  • Two gates are used in half adder digital circuit, namely XOR and AND gate.
  • There are two inputs and two outputs to half adder circuit.
  • Input: A and B any digital data
  • Output: Sum (S) and Carry (C) of input digits A and B
  • XOR gate is used to carry out the sum of two input digits and AND gate is used to calculate the carry if present.
  • Truth table of half adder circuit:

Truth table of Half adder

When both the inputs are low or high then Sum will be 0 and when both the inputs are high then sum is 1. Carry is high only when both the inputs are high.

A

B

Sum

Carry

0

0

0

0

0

1

1

0

1

0

1

0

1

1

0

1

Question number: 2

» Aptitude

Short Answer Question▾

Write in Short

The girl’s age is twice that of boy, if the boy is four years old. After four years what will be the age of girl?

Explanation

At present,

Boy’s age, b = 4 years

Girl’s age, g = 2b = 8 years

After 4 years

Boy’s age, = b + 4 = 8 years

Girl’s age, = g + 4 = 12 years

After 4 years age of girl will be 12 years.

Question number: 3

» Aptitude

Short Answer Question▾

Write in Short

Y catches 5 times more fishes than X. If total number of fishes caught by X and Y is 42, then number of fishes caught by X?

Explanation

Here, Y catches 5 times more fishes than X. So, Y = 5X

And total number of fishes caught by X and Y is 42. So, X + Y = 42

Substituting the value of Y in terms of X

We can get, X + 5X = 42

6X = 42

X = 7