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Units and Measurements question

2019 · 9 Apr · Shift 2 · Q58
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Units and Measurements question

2019 · 9 Apr · Shift 2 · Q58

JEE MainPhysicsUnits and MeasurementsMCQ+4 / −1
The area of a square is 5.29 cm2. The area of 7 such squares taking into account the significant figures is :-
  1. A
    37.0 cm2
  2. B
    37 cm2
  3. C
    37.030 cm2
  4. D
    37.03 cm2
View written solutionFree

Correct answer: A

  1. Given data

    Area of one square = 5.29 cm25.29\,\text{cm}^25.29cm2

    Number of squares = 777

  2. Find total area

    Total area=7×5.29=37.03 cm2\text{Total area} = 7 \times 5.29 = 37.03\,\text{cm}^2Total area=7×5.29=37.03cm2

  3. Apply significant figures rule

    In multiplication, the result should have the same number of significant figures as the factor with the least number of significant figures.

    • 5.295.295.29 has 3 significant figures.
    • 777 is a counted number (exact number of squares), so it does not limit significant figures.

    Therefore, the answer should be reported with 3 significant figures.

  4. Round the result

    37.03→37.037.03 \to 37.037.03→37.0

    since 37.037.037.0 has 3 significant figures.

  5. Check options

    • A: 37.0 cm237.0\,\text{cm}^237.0cm2 ✅
    • B: 37 cm237\,\text{cm}^237cm2 has only 2 significant figures ❌
    • C: 37.030 cm237.030\,\text{cm}^237.030cm2 has too many significant figures ❌
    • D: 37.03 cm237.03\,\text{cm}^237.03cm2 has too many significant figures ❌

Hence, the correct answer is A.

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