Answer:
a)
And we can conclude that we are 95% confident that the true mean of Co2 level is between 608.29 and 700.03 ppm
b)
Step-by-step explanation:
Part a
The confidence interval for the mean is given by the following formula:
(1)
In order to calculate the critical value
we need to find first the degrees of freedom, given by:
Since the Confidence is 0.95 or 95%, the value of
and
, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,51)".And we see that
Replacing we got:
And we can conclude that we are 95% confident that the true mean of Co2 level is between 608.29 and 700.03 ppm
Part b
The margin of error is given by :
(a)
The desired margin of error is ME =50/2=25 and we are interested in order to find the value of n, if we solve n from equation (a) we got:
(b)
The critical value for 95% of confidence interval now can be founded using the normal distribution. And in excel we can use this formla to find it:"=-NORM.INV(0.025;0;1)", and we got
, and we use an estimator of the population variance the value of 175 replacing into formula (b) we got:
Answer:
75/4=3/100
Step-by-step explanation:
sinple this is on proportion
if you want crisscross the fraction
Answer:
Step-by-step explanation:
Assumed the starting point is the sea level 0.
<u>After 2.8 min the diver is at position:</u>
- 20 1/2 * 2.8 =
- 20.5 * 2.8 =
- 57.4 feet below sea level
<u>The position change after next 2 minutes:</u>
<u>The position of the diver after 4.8 min:</u>
- 57.4 - 50 = 7.4 feet below sea level
Answer: 150 boys
Step-by-step explanation:
Let the number of boys be x
Since there were 200 more girls than boys, the number of girls will be: = x + 200
Since the ratio of boys to girls was 3:7, this can be solved further below:
3/7 = x/x+200
Cross multiply
(7 × x) = 3(x + 200)
7x = 3x + 600
7x - 3x = 600
4x = 600
x = 600/4
x = 150
The number of boys enrolled is 150
Number of Girls will be:
= X + 200
= 150 + 200
= 350
Check: Number of boys / Number of girls
= 150/350
= 3/7
= 3:7