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A camera shop stocks eight different types of batteries, one of which is type A7

ID: 3009254 • Letter: A

Question

A camera shop stocks eight different types of batteries, one of which is type A7b. Assume there are at least 30 batteries of each type. How many ways can a total inventory of 30 batteries be distributed among the eight different types? How many ways can a total inventory of 30 batteries be distributed among the eight different types if the inventory must include at least four A76 batteries? How many ways can a total inventory of 30 batteries be distributed among the eight different types if the inventory includes at most three A7b batteries?

Explanation / Answer

a) Given that one is of type A7B.

Hence other 29 batteries should be of the remaining 7 types

First battery can be any one of the 7, II also any one of the 7,,,, and so on.

Hence total number of distribution =729

2) Now we have 4 A7B , or 5A7b or 6 A7b,... 30A7b

Total no of ways if no restriction is there = 830

No of ways for atleast 4 = total ways - no of ways for 0,1,2,3

= 830-(730+ 729 + 728+ 727)

c) If atmost 3 means no of ways

= (730+ 729 + 728+ 727)