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ISRO EC 2023 Q.83: solution and answer

ISRO 2023 · ECQ.83 · 2 marks · MCQ

Which option replaces the question mark?

ISRO EC 2023 question 83: Top panel: four example rules.Tap to open full size
Figure from the ISRO EC 2023 paper. It is part of the question.
Figure description

Top panel: four example rules. (1) A green circle with a plus turns a box of filled square, slash, outline circle into a box with a half-size filled square, slash, circle. Caption: Makes 1st item Half size. (2) A green circle with a filled dot turns outline circle, slash, double arrow into filled circle, slash, double arrow. Caption: Shades 1st item. (3) A green circle with an x turns outline circle, filled crescent, filled square into outline circle, filled cup shape (the crescent rotated), filled square. Caption: Rotates 2nd item 90 degrees anticlockwise. (4) A green swirl symbol turns filled square, crescent, outline circle into outline circle, filled square, crescent. Caption: Shifts all items one position right. Main panel: an input box with a large filled dark-blue square, an outline circle and an outline crescent; an arrow passes through two operators in sequence, a green circle with a filled green dot (shade) and then a green circle with a plus (half size), leading to a box with a question mark. Four answer boxes: A has a small unfilled square, an outline circle and a crescent. B has a small filled square, an outline circle and an outline crescent. C has a large filled square, a small filled circle and a crescent. D has a small filled square, a large outline circle and a large filled crescent.

  1. (A)

    Small unfilled square, outline circle, outline crescent

  2. (B)

    Small filled square, outline circle, outline crescent

  3. (C)

    Large filled square, small filled circle, outline crescent

  4. (D)

    Small filled square, large outline circle, large filled crescent

Answer and solution

ANSWER

The missing box is a small filled square, an outline circle and an outline crescent, which is option B.

Official answer: BSource: ISRO's revised and final answer key of 16 February 2024

  1. Read the operators from the example boxes. The green circle with a filled dot shades only the 1st item. The green circle with a plus makes only the 1st item half its size. The other items are not changed by either operator.

  2. The input box holds a large filled square, an outline circle and an outline crescent. Both operators act on the 1st item, the square, and the other two items stay as they are.

  3. Apply the shade operator first. The square is already filled, so it stays a filled square.

  4. Apply the half-size operator. The filled square becomes a small filled square.

  5. The result is a small filled square, an outline circle (unchanged) and an outline crescent (unchanged).

  6. Compare with the options. A has an unfilled square, so the shading is lost. C keeps the square large and shades the circle, which no rule does. D enlarges the circle and crescent and fills the crescent, which no rule does. Only B matches.

KEY IDEA

Work out which item each operator acts on. Both operators here change only the 1st item, so the 2nd and 3rd items pass through untouched.

WATCH OUT FOR

Applying shade or half-size to every item in the box, or forgetting that an already filled square gains nothing from shading. That leads to option C or D.

From the ISRO EC 2023 paper. Also Q.83 of the ISRO Scientist/Engineer Computer Science 2023 paper. Every question of this paper · The full paper (PDF, ISRO) · All 7 ISRO Spatial questions, with notes

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