# Test: Probability I - Normal

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Question 1:   The box fits $\text{\hspace{0.17em}}15\text{\hspace{0.17em}}$ different items:  $7$ pencils and $\text{\hspace{0.17em}}8\text{\hspace{0.17em}}$ pens. $\text{\hspace{0.17em}}3\text{\hspace{0.17em}}$ pencils and $\text{\hspace{0.17em}}5\text{\hspace{0.17em}}$ pens are taken off the box randomly. How many elementary consequences are possible here?
${C}_{7}^{3}×{C}_{8}^{5}$
$8!$
${C}_{7}^{3}+{C}_{8}^{5}$
${C}_{15}^{8}$
Question 2:   During the exam session, professor graded his students' tests. Out of $\text{\hspace{0.17em}}100\text{\hspace{0.17em}}$ students, $\text{\hspace{0.17em}}15\text{\hspace{0.17em}}$ got "A", $\text{\hspace{0.17em}}28\text{\hspace{0.17em}}$ got "B", $\text{\hspace{0.17em}}40\text{\hspace{0.17em}}$ got "C", $\text{\hspace{0.17em}}17\text{\hspace{0.17em}}$ students failed the test. What was the probability $\text{\hspace{0.17em}}p\left(A\right)\text{\hspace{0.17em}}$ not to fail this test?
$0.17$
$0.83$
$0.15$
$0.5$
Question 3:   There are $\text{\hspace{0.17em}}6\text{\hspace{0.17em}}$ blue and $\text{\hspace{0.17em}}9\text{\hspace{0.17em}}$ red pens in the box. What is the least amount of pens you should randomly pick to pick a blue pen with guarantee?
$10$
$15$
$1$
$6$
Question 4:   A group of scientists are providing an experiment on simultaneous tossing of $\text{\hspace{0.17em}}5\text{\hspace{0.17em}}$ coins. The result of the experiment is the final amount of tails that will drop out. How many possible consequences can be at the end of this experiment?
$6$
$5$
$3$
$10$
Question 5:   After some calculations, it was determined that the probability of hitting the target is $\text{\hspace{0.17em}}25%\text{\hspace{0.17em}}$ . Is it possible that after $\text{\hspace{0.17em}}100\text{\hspace{0.17em}}$ shots there will be $\text{\hspace{0.17em}}98\text{\hspace{0.17em}}$ hits?
No
Yes, only if probability of hitting the target is increased.
Yes, only if number of hits will increase.
Yes
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