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A book contains \[\mathbf{85}\] pages. A page is chosen at random. What is the probability that the sum of the digits on the page is \[\mathbf{8}\]?
A book contains \[\mathbf{85}\] pages. A page is chosen at random. What is the probability that the sum of the digits on the page is \[\mathbf{8}\]?
CBSE | Class 10 | Exercise 13.2 | Selina | Statistics and Probability
A book contains \[\mathbf{85}\] pages. A page is chosen at random. What is the probability that the sum of the digits on the page is \[\mathbf{8}\]?

Solution:

We know that,

Number of pages in the book \[=\text{ }85\]

Number of possible outcomes \[=\text{ }n\left( S \right)\text{ }=\text{ }85\]

Out of \[85\]pages, pages that sum up to \[8\text{ }=\text{ }\left\{ 8,\text{ }17,\text{ }26,\text{ }35,\text{ }44,\text{ }53,\text{ }62,\text{ }71,\text{ }80 \right\}\]

So, pages that sum up to \[8\text{ }=\text{ }n\left( E \right)\text{ }=\text{ }9\]

Hence, probability of choosing a page with the sum of digits on the page equals \[8\text{ }=\text{ }n\left( E \right)/\text{ }n\left( S \right)\text{ }=\text{ }9/85\]

 

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