A questions paper which is divided into two groups containing three and four questions respectively carries the note that it is not necessary to answer all the questions. One question must be answered from each group. In how many ways can an examinee select the questions?
A questions paper which is divided into two groups containing three and four questions respectively carries the note that it is not necessary to answer all the questions. One question must be answered from each group. In how many ways can an examinee select the questions?
Option 1 -
15
Option 2 -
75
Option 3 -
105
Option 4 -
104
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1 Answer
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Correct Option - 4
Detailed Solution:In the first group, one question can be selected or can be rejected; so three questions can be dealt with in 2 * 2 * 2 ways, but this includes the case when all three questions have been left; so they can be selected in 23 – 1 = 7 ways. Similarly four questions of the second group can be selected in 24 – 1 = 15 ways. Thus all seven questions can be selected in 15 * 7 = 105 ways; but this includes the case when all questions have been solved; hence leaving that case, total number of ways required is 105 – 1 = 104
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