Answered

Westonci.ca offers quick and accurate answers to your questions. Join our community and get the insights you need today. Connect with a community of experts ready to help you find solutions to your questions quickly and accurately. Join our platform to connect with experts ready to provide precise answers to your questions in different areas.

how many 3 element subsets of {1, 2, 3, 4, 5, 6, 7, 8, ,9, 10, 11} are there for which the sum of the elements in the subset is a multiple of 3

Sagot :

akiran007

Answer:

There are 155 ways in which these elements casn occur.

Step-by-step explanation:

We want 3 element subsets whose sum are multiples of 3

1+2+3= 6

1+2+6= 9

1+2+9= 12

1+9+11=21

1+3+5=9

1+4+8=12

1+5+6=12

1+6+8=15

1+7+10=18

1+8+9=18

1+9+11=21

2+3+7=12

2+4+6=12

2+4+9=15

2+5+11=18

2+6+7=15

2+7+9=18

2+8+5=15

2+8+11=21

2+9+10=21

3+6+9= 18

3+9+11=21

3+10+11=24

6+9+10=27

6+8+11=27

6+7+11=24

7+8+9= 24

8+9+10=27

7+9+11=27 .........

We have 11 elements

We need a combination of 3

The combinations can be in the form

even+ even+ odd

odd+odd+odd

even + odd+odd

So there are 3 ways in which these elements can occur

Total number of combinations with  3 elements =11C3= 165

There are 6 odd numbers and 5 even numbers.

Number of subsets with 3 odd numbers = 6C3= 20

Number of two even numbers and 1 odd number = 5C2*6C1=10*6= 60

Number of 2 odd and 1 even number = 6C2* 5C1= 5*15= 75

So 20+60+75=155

There are 155 ways in which this combination can occur

Thank you for trusting us with your questions. We're here to help you find accurate answers quickly and efficiently. We hope you found this helpful. Feel free to come back anytime for more accurate answers and updated information. Thank you for trusting Westonci.ca. Don't forget to revisit us for more accurate and insightful answers.