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.
Answer:
y=-4, x=1
Step-by-step explanation:
2x-y=6 x+y=-3
2(-3-y)-y=6 x=-3-y
-6-2y-y=6 x=-3+4
-3y=12 x=1
y=-4
Answer:
274.84 gallons.
Step-by-step explanation:
Divide 3,298 by 12
3298/12 =274.84
In addition to mean and sample size you will need the individual scores.
The formula for standard deviation is:
S^2 = E(X-M)^2/N-1
Here's an example:
Data set: 4,4,3,1
Mean: 3
Sample size: 4
First, put the individual scores one after the other and subtract the mean from it.
4 - 3 = 1
4 - 3 = 1
3 - 3 = 0
1 - 3 = -2
Second, square the answers you got from step 1.
1^2 = 1
1^2 = 1
0^2 = 0
-2^2 = 4
Third, plug the values from step 2 into the formula.
S^2 = (1+1+0+4)/(4-1) = 6/3 = 2
Standard deviation = 2
