Question 1173542
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There are _____ways that a student can answer the exam with 7 correct answers and 8 incorrect answers.
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<pre>
It is assumed (although does not formulated explicitly in the problem) that there are 8+7 = 15 questions, in all.



There are  {{{C[15]^7}}}  ways to select 7 questions from 15 questions to answer them correctly.


The rest questions will be automatically answered incorrectly.


Your  <U>ANSWER</U>  is  {{{C[15]^7}}} = {{{(15!)/(7!*8!)}}} = {{{(15*14*13*12*11*10*9)/(1*2*3*4*5*6*7)}}} = 6435 ways.
</pre>

Solved.



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Actually, the problem in the post is worded INCORRECTLY.


The correct wording is


<pre>
    There are  15   questions  at an exam.

    In how many ways the student may answer 7 questions of them correctly ?
</pre>


I observe it very often at this forum that the "local composers" formulate their problems INCORRECTLY, 

because they do not know the subject professionally.