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Probability — Maths STD 10 — Question

CBSE BoardEnglish MediumSTD 10MathsProbability4 Marks
Question
Computer-based learning (CBL) refers to any teaching methodology that makes use of computers for information transmission. At an elementary school level, computer applications can be used to display multimedia lesson. A survey was done on 1000 elementary and secondary schools of Assam and they were classified by the number of computers they had.
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Number of Computers1-1011-2021-5051-100101 and more
Number of Schools25020029018080

One school is chosen at random. Then:
(i) Find the probability that the school chosen at random has more than 100 computers.
(ii) Find the probability that the school chosen at random has 50 or fewer computers.
(iii) Find the probability that the school chosen at random has not more than 20 computers.
(iv) Find the probability that the school chosen at random has 10 or less than 10 computers.
✓

Answer

(i) Total number of schools = 1000
Number of schools having more than 100 computers = 80
∴ Probability that the school chosen at random has more than 100 computers $=\frac{80}{1000}=0.08$
(i) Number of schools having 50 or fewer computers = 250 + 200 + 290 = 740
∴ Required probability $=\frac{740}{1000}=0.74$
(ii) Number of schools having not more than 20 computers = 250 + 200 = 450
∴ Required probability $=\frac{450}{1000}=0.45$
(iv) Number of schools having 10 or less than 10 computers = 250
∴ Required probability $=\frac{250}{1000}=0.25$

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