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Quantitative Aptitude

GATE CSE 2026 Set 1 · Q10

MCQ2 marksEasy

Time

An unbiased six-faced dice whose faces are marked with numbers 1, 2, 3, 4, 5, and 6 is rolled twice in succession and the number on the top face is recorded each time. The probability that the number appearing in the second roll is an integer multiple of the number appearing in the first roll is ___________

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Solution

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Official answer: C) (7)/(18)

Quantitative Aptitude

Let (x,y)(x, y) denote the outcome of the two rolls, where xx is the number on the first roll and yy is the number on the second roll.

The total number of possible outcomes when rolling a six-faced die twice is:

n(S)=6×6=36n(S) = 6 \times 6 = 36

We need to find the number of favorable outcomes where yy is an integer multiple of xx (y=kxy = kx for some positive integer kk):

  • For x=1x = 1: y∈{1,2,3,4,5,6}  ⟹  6y \in \{1, 2, 3, 4, 5, 6\} \implies 6 outcomes

  • For x=2x = 2: y∈{2,4,6}  ⟹  3y \in \{2, 4, 6\} \implies 3 outcomes

  • For x=3x = 3: y∈{3,6}  ⟹  2y \in \{3, 6\} \implies 2 outcomes

  • For x=4x = 4: y∈{4}  ⟹  1y \in \{4\} \implies 1 outcome

  • For x=5x = 5: y∈{5}  ⟹  1y \in \{5\} \implies 1 outcome

  • For x=6x = 6: y∈{6}  ⟹  1y \in \{6\} \implies 1 outcome

Total number of favorable outcomes:

n(E)=6+3+2+1+1+1=14n(E) = 6 + 3 + 2 + 1 + 1 + 1 = 14

Therefore, the required probability is:

P(E)=n(E)n(S)=1436=718P(E) = \frac{n(E)}{n(S)} = \frac{14}{36} = \frac{7}{18}

Hence, the correct option is C.

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This Quantitative Aptitude previous year question is Q10 of the GATE CSE 2026 Set 1 paper. Find more GATE CSE PYQs on Quantitative Aptitude in General Aptitude, or browse all GATE CSE PYQs.

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Quantitative Aptitude in GATE CSE

Quantitative Aptitude has 53 GATE CSE PYQs across 13 papers from 2011 to 2026. 27 of them are 2-mark MCQs like this one, and GATE CSE 2026 Set 1 has 4.

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GateAI solution cardGATE CSE 2026 Set 1 · Q10 · MCQ

An unbiased six-faced dice whose faces are marked with numbers 1, 2, 3, 4, 5, and 6 is rolled twice in succession and the number on the top face is recorded each time. The probability that the number appearing in the second roll is an integer multiple of the number appearing in the first roll is …

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