Question

Out of first 20 natural numbers 3 numbers are selected such that there is exactly one even number

Answer 1

Answer:

Step-by-step explanation:

No. Of even from 1 to 20 =10

No. Of odd from 1 to 20 = 10

Now the selection can be made considering no number is repeated

Out of 10 even number 1 has to selected so there are

(101)=10 ways. Now out of 10 odd numbers we have to choose 2 so (102)=10×9=90

Total number of ways when the numbers are distinct = 10×90=900

Now if numbers can be same then in case of even number similar to above we have 10 choices and in case of odd, we have 102 choices. So total we have 10×102=1000 choices.

Answer 2

Answer:

1+2+3=6

Step-by-step explanation:

Because 6 is even