Question

Teesha is in the french club. there are 21 students in the club. the french teacher will pick two students at random to guide visiting students from france. what is the probability that teesha will not be picked as a guide?

Answer 1

19/21. You can get this answer by deducting 2/21 which is the probability of Teesha being picked from 1.

Answer 2

1.1053

Step-by-step explanation:

Given that;

there are total of 21 students in the club &

the teacher will pick two students at random

Therefore; the number of combination in the total of 21 students

C₂₁,₂ =
`(21!)/((2!)(19!))`

=
`(21*20*19!)/((2*1)(19!))`

=
`(420)/(2)`

= 210

Similarly, let's determine the numer of ways in which Teesha will not be picked. since Teesha will not be picked; we have :

Total population of students - Teesha

= 21 - 1

= 20

Then the number of combinations will be:

C₂₀,₂ =
`(20!)/((2!)(18!))`

=
`(20*19*18!)/((2*1)(18!))`

=
`(380)/(2)`

= 190

∴ The probability that Teesha will not be picked =
`(210)/(190)`

=1.1053