Answer:
a) The formula is given by mean 
the margin of error. Where the margin of error is the product between the critical value from the normal standard distribution at the confidence level selected and the standard deviation for the sample mean.
b) 
Step-by-step explanation:
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
If the distribution for X is normal or if the sample size is large enough we know that the distribution for the sample mean 
is given by:
Part a
The formula is given by mean the margin of error. Where the margin of error is the product between the critical value from the normal standard distribution at the confidence level selected and the standard deviation for the sample mean.
Part b
The confidence interval for the mean is given by the following formula:
Answer:
1.49 hrs or 1 hr and 30 minutes approximately
Step-by-step explanation:
if fran go 2.8m up then the river flow at a rate of 0.8m; the since we are taking the speed of fran and river to be constant. the ratio between their speed will always remain constant. that is if 0.8/2.8 = 0.286≈ this will be always constant.
so if he go up 4m then the horizontal length has to be 1.143 because 1.143/4 = 0.286.
now we find the distance between frans initial positon and final position. to find it we use pythagoras theorem.
to find the time divide distance traveled by speed;
4.160/2.8 = 1.49 hrs
-47,-21,-13,6,9,49,63,69 I think is the answer
Answer:each album costs $7 and you buy x of them
cost of albums = 7x
each movie costs $8 and you have you have y of them
cost of movies = 8y
total cost is has to be less than $47
---> 7x + 8y < 47
sketch the graph of 7x + 8y = 47 , a straight line, and shade in the region below that line. Of course you would stay in the first quadrant, (x > 0, and y >0 , since you can't have negative number of movies and albums)
Since you can't buy partial albums and movies, both x and y have to be whole numbers.
So for solutions you would consider only ordered pairs that have whole numbers as their components.
e.g. (2, 2) or (1,5)
Step-by-step explanation: Hope this helps :)
