SOLUTION: From a survey involving​ 1,000 university​ students, a market research company found that 750 students owned​ laptops, 410 owned​ cars, and 370 owned cars and laptops.

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Question 1197700: From a survey involving​ 1,000 university​ students, a market research company found that 750 students owned​ laptops, 410 owned​ cars, and 370 owned cars and laptops. If a university student is selected at​ random, what is each​ (empirical) probability?
​(A) The student owns either a car or a laptop
​(B) The student owns neither a car nor a laptop

Answer by ikleyn(52786) About Me  (Show Source):
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From a survey involving​ 1,000 university​ students, a market research company found
that 750 students owned​ laptops, 410 owned​ cars, and 370 owned cars and laptops.
If a university student is selected at​ random, what is each​ (empirical) probability?
​(A) The student owns either a car or a laptop
​(B) The student owns neither a car nor a laptop
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(A)  This question asks "either a car or a laptop, but not both".

     We compute this amount as 

          (n(car) + n(laptop) - n(both)) - n(both) = (750+410-370) - 370 = 420.


     Thus the probability is  P(question A) = 420%2F1000 = 42%2F100 = 21%2F50 = 0.42 = 42%.      ANSWER



(B)  This question asks about the complementary probability to having a car OR a laptop.

     The number of students who own a car or a laptop is

         n(car) + n(laptop) - n(both) = 750 + 410 - 370 = 790.


      Thus the probability is  P(question B) = %281000-790%29%2F1000 = 21%2F100 = 0.21 = 21%.      ANSWER

Solved.


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In this problem, the key subject to learn is the difference in calculating  " either - or "  from calculating single  " or ".


                        To memorize :

        The single  " or "  is  " or inclusive ".

        The  " either-or "  is  " or exclusive ".