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Two dice are thrown simultaneously. What is the probability that 4 will come up on at least one die?

Solution

✅ Correct Option: 1

When two dice are thrown simultaneously, we need to find the probability that at least one die shows a 4.

"At least one" means one 4 or two 4s (i.e., not zero 4s).


When throwing 2 dice:

First die has 6 possible outcomes: 1, 2, 3, 4, 5, 6

Second die has 6 possible outcomes: 1, 2, 3, 4, 5, 6

Total possible outcomes =6×6=36= 6 \times 6 = 36


Using the complement method, we find the probability of not getting any 4, then subtract from 1.

For the first die to not show 4:

Possible outcomes: 1, 2, 3, 5, 6 (5 outcomes)

P(no 4 on first die)=56P(\text{no 4 on first die}) = \dfrac{5}{6}

For the second die to not show 4:

P(no 4 on second die)=56P(\text{no 4 on second die}) = \dfrac{5}{6}

For both dice to not show 4:

P(no 4 on either die)=56×56P(\text{no 4 on either die}) = \dfrac{5}{6} \times \dfrac{5}{6}

=2536= \dfrac{25}{36}


P(at least one 4)=1−P(no 4 on either die)P(\text{at least one 4}) = 1 - P(\text{no 4 on either die})

=1−2536= 1 - \dfrac{25}{36}

=3636−2536= \dfrac{36}{36} - \dfrac{25}{36}

=1136= \dfrac{11}{36}

Therefore, the probability that 4 will come up on at least one die is 1136\dfrac{11}{36}.

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