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There are several chocolate ice-creams, several vanilla ice-creams, several mango ice-creams and several butterscotch ice-creams displayed in the ice-cream parlour. What is the number of ways of selecting 10 ice-creams in total from them?

Option: 1

326


Option: 2

286


Option: 3

10^{4}


Option: 4

Cannot be determined


Answers (1)

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Note the following:

  • The formula for the combination for the selection of the \mathrm{x} items from the \mathrm{y}different items is \mathrm{=^{y}C_{x}=\frac{y!}{x!\left ( y-x \right )!}}

  • The number of ways of allocating the \mathrm{n}identical items among \mathrm{r} head count with zero, one or more items is \mathrm{=^{n+r-1}C_r-1}

As per the available data, the number of identical types of ice-creams is =1+1+1+1=4

Note that the following is evident from the provided data.

  • The number from which the restricted combination is to be made is\mathrm{=n+r-1=10+4-1=13}.

  • The number with which the restricted combination is to be made is \mathrm{=r-1=4-1=3}

Therefore, the required restricted combination is

=\mathrm{^{n+r-1}C_{r-1}}

=\mathrm{^{13}C_{3}}

=\frac{13!}{ 3!10!}

=286

 

Posted by

Rishabh

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