Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Probability question

2021 · 17 Mar · Shift 1 · Q30
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Mathematics
  4. /Probability
  5. /2021 · 17 Mar · Shift 1 · Q30

Probability question

2021 · 17 Mar · Shift 1 · Q30

JEE MainMathematicsProbabilityMCQ+4 / −1
Two dies are rolled. If both dices have six faces numbered 1, 2, 3, 5, 7 and 11, then the probability that the sum of the numbers on the top faces is less than or equal to 8 is :
  1. A
    49{4 \over 9}94​
  2. B
    12{1 \over 2}21​
  3. C
    512{5 \over {12}}125​
  4. D
    1736{17 \over {36}}3617​
View written solutionFree

Correct answer: D

  1. Total possible outcomes

Each die has 6 faces labeled: {1,2,3,5,7,11}\{1,2,3,5,7,11\}{1,2,3,5,7,11}

When two dice are rolled, total number of equally likely ordered outcomes is: 6×6=366 \times 6 = 366×6=36

  1. We need outcomes with sum ≤8\le 8≤8

Let us count favorable ordered pairs (a,b)(a,b)(a,b) where a+b≤8a+b \le 8a+b≤8 with a,b∈{1,2,3,5,7,11}a,b \in \{1,2,3,5,7,11\}a,b∈{1,2,3,5,7,11}.

We check each possible value on the first die.

  • If first die shows 111, then second die can be: 1,2,3,5,71,2,3,5,71,2,3,5,7 since 1+1=2,  1+2=3,  1+3=4,  1+5=6,  1+7=81+1=2,\;1+2=3,\;1+3=4,\;1+5=6,\;1+7=81+1=2,1+2=3,1+3=4,1+5=6,1+7=8 but 1+11=12>81+11=12>81+11=12>8 So, favorable outcomes = 555.

  • If first die shows 222, then second die can be: 1,2,3,51,2,3,51,2,3,5 since 2+1=3,  2+2=4,  2+3=5,  2+5=72+1=3,\;2+2=4,\;2+3=5,\;2+5=72+1=3,2+2=4,2+3=5,2+5=7 but 2+7=9>8,  2+11=13>82+7=9>8,\;2+11=13>82+7=9>8,2+11=13>8 So, favorable outcomes = 444.

  • If first die shows 333, then second die can be: 1,2,3,51,2,3,51,2,3,5 since 3+1=4,  3+2=5,  3+3=6,  3+5=83+1=4,\;3+2=5,\;3+3=6,\;3+5=83+1=4,3+2=5,3+3=6,3+5=8 but 3+7=10>8,  3+11=14>83+7=10>8,\;3+11=14>83+7=10>8,3+11=14>8 So, favorable outcomes = 444.

  • If first die shows 555, then second die can be: 1,2,31,2,31,2,3 since 5+1=6,  5+2=7,  5+3=85+1=6,\;5+2=7,\;5+3=85+1=6,5+2=7,5+3=8 but 5+5=10>85+5=10>85+5=10>8 So, favorable outcomes = 333.

  • If first die shows 777, then second die can be: 111 since 7+1=87+1=87+1=8 but all others give sum greater than 888. So, favorable outcomes = 111.

  • If first die shows 111111, then no value on second die works, because 11+1=12>811+1=12>811+1=12>8 So, favorable outcomes = 000.

  1. Total favorable outcomes

5+4+4+3+1+0=175+4+4+3+1+0=175+4+4+3+1+0=17

  1. Probability

P(sum≤8)=1736P(\text{sum} \le 8)=\frac{17}{36}P(sum≤8)=3617​

  1. Compare with options

The probability is 1736\boxed{\frac{17}{36}}3617​​ which is Option D.

  1. Comparison with stored correct answer

Stored correct answer: D

Our derived answer: D

So, the stored answer is correct.

PreviousNext

More from Probability

  • Let there be three independent events E1, E2 and E3. The probability that only E1 occurs is α, only E2 occurs is β and only E3 occurs is γ. Let 'p' denote the probability of none of events occurs that satisfies the…2021 · Numerical
  • Let a computer program generate only the digits 0 and 1 to form a string of binary numbers with probability of occurrence of 0 at even places be 21​ and probability of occurrence of 0 at the odd place be 31​. Then the…2021 · MCQ
  • Words with or without meaning are to be formed using all the letters of the word EXAMINATION. The probability that the letter M appears at the fourth position in any such word is :2021 · MCQ
  • The probability of selecting integers a ∈[− 5, 30] such that x2 + 2(a + 4)x − 5a + 64 > 0, for all x ∈ R, is :2021 · MCQ
  • Let A, B and C be three events such that the probability that exactly one of A and B occurs is (1 − k), the probability that exactly one of B and C occurs is (1 − 2k), the probability that exactly one of C and A occurs is (1 − k) and…2021 · MCQ
  • Four dice are thrown simultaneously and the numbers shown on these dice are recorded in 2 × 2 matrices. The probability that such formed matrix have all different entries and are non-singular, is :2021 · MCQ
  • Let Bi (i = 1, 2, 3) be three independent events in a sample space. The probability that only B1 occur is α, only B2 occurs is β and only B3 occurs is γ. Let p be the probability that none of the events Bi occurs and…2021 · Numerical
  • The probability that two randomly selected subsets of the set {1, 2, 3, 4, 5} have exactly two elements in their intersection, is :2021 · MCQ