Question 1163048
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Q1) [] In how many ways can 5 boys and 4 girls be seated in a row so that those of the same gender sit together?
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Case 1: BBBBBGGGG

5!4! = (120)(24) = 2880

Case 2: GGGGBBBBB

Same: 2880

Answer: 2880+2880 = 5760
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Q3) [] A class has 12 boys and 4 girls. If 3 students are selected at random from the class, what is the probability p that they are all boys?<pre>

 12 boys CHOOSE 3     12C3     220      11
------------------ = ------ = ------ = ----
16 people CHOOSE 3    16C3     560      28
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Q5) [] A student is to answer 8 out of 10 questions on an exam. How many choices has he if he must answer the first 3 questions?
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The student has to answer the other 8-3=5 out of the remaining 10-3=7

7 questions CHOOSE 5 = 7C5 = 21
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Edwin</pre>