The circumference and
Abacus
Answer:
c. (12.12, 18.48)
Step-by-step explanation:
Hello!
The study variable is X: number of times a racehorse is raced during its career.
The average number is X[bar]= 15.3 and the standard deviation is S= 6.8 obtained from a sample of n=20 horses.
To estimate the population mean you need that the variable has a normal distribution, in this case, we have no information about its distribution so I'll assume that it has a normal distribution. With n=20 the most accurate statistic to use for the estimation is a Students-t for one sample, the formula for the interval is:
X[bar] ± 

[15.3 ± 2.093 *
]
[12.12; 18.48]
Using a significance level of 95% you'd expect that the true average of times racehorses are raced during their career is included in the interval [12.12; 18.48].
I hope it helps!
I recommend using a calculator, but working out the problem manually is alright too. Be sure to check your answer to make sure it's correct by looking over your work or by multiplying two of the numbers to see if it equals the third. The answer is about .92.
3x+2(3x-3)=2
9x-6=2
9x=8
X=8/9
Answer:
The mean of the sampling distribution of p is 0.75 and the standard deviation is 0.0306.
Step-by-step explanation:
Central Limit Theorem:
For a proportion p in a sample of size n, the sampling distribution of the sample proportion will be approximately normal with mean
and standard deviation 
75% of teenagers in North America are pursuing a goal they have set for themselves.
This means that 
Sample of 200.
This means that
.
What are the mean and standard deviation of the sampling distribution of p?
By the Central Limit Theorem
Mean 
Standard deviation 
The mean of the sampling distribution of p is 0.75 and the standard deviation is 0.0306.