Answer:

Step-by-step explanation:
The confidence interval for the population mean x can be calculated as:

Where x' is the sample mean, s is the population standard deviation, n is the sample size and
is the z-score that let a proportion of
on the right tail.
is calculated as: 100%-99%=1%
So, 
Finally, replacing the values of x' by 308, s by 17, n by 15 and
by 2.576, we get that the confidence interval is:

Answer:
2/3
Step-by-step explanation:
Answer:
√20,
√19,
√17,
√23
Step-by-step explanation:
Answer:
x= -19
y= -14
Step-by-step explanation:
Substitution.
It tells you what y is already. You substitute that into the second equation and then solve. Then you use that answer and substitute it back into the first equation's x, and then you'll get your full answer.
Hope this helps <3
4:1/6 if you add all the instruments you get 120 then you divide it by six and you get 20 snare drums