Answer:
1/4
Step-by-step explanation:
Mrs. Lincoln has 15 girls and 10 boys in her homeroom. She randomly selects two students. The total number of students is 25.
The probability of choosing one girl is:
15 / 25 = 3 / 5
Now, 24 students are left.
The probability of choosing one boy is:
10 / 24 = 5 / 12
Therefore, the probability of choosing one girl and one boy is:
3 / 5 * 5 / 12
= 3 / 12
= 1/4
For large sample confidence intervals about the mean you have:
xBar ± z * sx / sqrt(n)
where xBar is the sample mean z is the zscore for having α% of the data in the tails, i.e., P( |Z| > z) = α sx is the sample standard deviation n is the sample size
We need only to concern ourselves with the error term of the CI, In order to find the sample size needed for a confidence interval of a given size.
z * sx / sqrt(n) = width.
so the z-score for the confidence interval of .98 is the value of z such that 0.01 is in each tail of the distribution. z = 2.326348
The equation we need to solve is:
z * sx / sqrt(n) = width
n = (z * sx / width) ^ 2.
n = ( 2.326348 * 6 / 3 ) ^ 2
n = 21.64758
Since n must be integer valued we need to take the ceiling of this solution.
n = 22
Answer:
1= A
2= C
Step-by-step explanation:
I think this is right I'm not sure but I think it is.
hope this helps :)
Hope this helped!
(Taken from a source but seemed right)
:)
10 runners ran fewer than 4 km
