Answer:
2/7
Step-by-step explanation:
There are 22 (12 + 10) total students in the class. That means that the chance of the first student picked being a girl is 12/22.
Now, we must calculate the chance of the next student to be picked <em>also </em>being a girl - however, there is a trap here! Remember that since a girl has been picked, the total student pool has decreased to 21 and and the total number of girls has decreased to 11. This means the new chance of girl being picked is 11/21.
To find the probability of both these events happening in conjunction, these fractions must be multiplied. 12/22 * 11/21 = 132/462, which simplifies to 2/7.
21.5.......:::..............:.::.::..
Answer:
Step-by-step explanation:
a₁₂ = a₁r¹²⁻¹ = -15×6¹¹
