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Hello students.
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Here we have the question is a student is taking an examination.
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A total of 15 christians out of this 15 he has to answer 10 questions.
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Okay, so we have the question is how many ways the 10 questions can be selected.
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And the second one, how many ways the 10 christians can be selected? if exactly two of the first three questions first be answered.
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So let me start with the first one, a part.
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So here we are going to use this equation, n, c, r, which is equal to n factorial, divided by n minus r factorial, multiplied by r factorial.
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Here, we have the total number is 15, out of which we need exactly 10 questions should be answered.
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So here it will be 15 factorial divided by 15 minus 10.
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That will be 5 factorial multiplied by 10 factorial.
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And this will be equal to 3003.
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3 ,000 and 3.
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In the second part, we also have to find the number of race for 10.
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But here we have to select two christians from we have to select two questions from the first three christians from first three christians...