Respuesta :
There are [tex]55[/tex] ways of these integers be selected to give a sum.
Given that:
It has [tex]12[/tex] consecutive integers .
Now,
Definition of consecutive integers :
" Consecutive integers are the integers that follow in the fixed sequence .
Consecutive integers is represented by [tex]n,n+1,n+2,n+3,....[/tex] where [tex]n[/tex] is an integer."
By given :
we have [tex]12[/tex] consecutive integers .
Thus,[tex]n=1[/tex] and substitute the equation is,
[tex]1,(n+1),(1+2),(1+3),(1+4),(1+5),(1+6),(1+7),(1+8),(1+9),(1+10),(1+11)\\\\\implies 1,2,3,4,5,6,7,8,9,10,11,12[/tex]
Now,
Split all the integers into 4 equal parts,
Part 1: Those integers are divisible by [tex]4[/tex] and the remainder be 0.
Then,
[tex]a=0(mod 4)[/tex]
Part 2: Those integer producing the remainder [tex]1[/tex] when it is divisible by [tex]4[/tex].
Then,
[tex]a=1(mod 4)[/tex]
Part 3: Those integer producing the remainder [tex]2[/tex] when it is divisible by[tex]4[/tex].
Then,
[tex]a=2(mod 4)[/tex]
Part 4: Those integer producing the remainder [tex]3[/tex] when it is divisible by[tex]4[/tex].
Then,
[tex]a=3(mod4)[/tex]
Since, three of these integers be selected to give a sum which divides by [tex]4[/tex] is,
In any 12 consecutive integers there are [tex]12\div4[/tex]
i.e. exactly 3 numbers of each category of mod4 namely ,
[tex]0(mod4), 1(mod4), 2(mod4), 3(mod4)[/tex]
Thus, the total combinations of above [tex]5[/tex] categories of sets of [tex]3[/tex] integers are
- All the 3 numbers are [tex]0(mod4)[/tex]
[tex]3C_1=3(1)=3[/tex]
- One number be [tex]0(mod4)[/tex] and other two numbers are [tex]2(mod4)[/tex]
[tex]3C_1*3C_2=3(1)*3=9[/tex]
- One number [tex]0(mod4)[/tex] and other numbers [tex]1(mod4)[/tex] & [tex]3(mod4)[/tex]
[tex]3C_1*3C_1*3C_1=3*3*3=27[/tex]
- Two numbers be [tex]1(mod4)[/tex] and one number be [tex]2(mod4)[/tex]
[tex]3C2 * 3C1 = 3*3 = 9[/tex]
- One number be [tex]2(mod4)[/tex] and two numbers be [tex]3(mod4)[/tex]
[tex]3C1 * 3C2 = 3*3 = 9[/tex]
Thus, sum of the total ways be [tex]12[/tex] consecutive integers of three integers is divisible by 4 is,
[tex]3+9+27+9+9=55[/tex]
Hence, it has [tex]55[/tex] ways.
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