Answer:
The probability that Albert's sample of 64 will have a mean between 13.5 and 16.5 minutes is 0.9973.
Step-by-step explanation:
Previous concepts
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".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Let X the random variable that represent interest on this case, and for this case we know the distribution for X is given by:
And let 
represent the sample mean, the distribution for the sample mean is given by:
On this case 
Solution to the problem
We are interested on this probability
If we apply the Z score formula to our probability we got this:
And we can find this probability on this way:
And in order to find these probabilities we can find tables for the normal standard distribution, excel or a calculator.
The probability that Albert's sample of 64 will have a mean between 13.5 and 16.5 minutes is 0.9973.
Answer: the answer is 200
Step-by-step explanation:
Answer:
At least 832 teenargers must be interviewed.
Step-by-step explanation:
We have that to find our 
level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of 
.
So it is z with a pvalue of 
, so 
Now, find the margin of error M as such
In which 
is the standard deviation of the population and n is the size of the sample.
How many teenagers must the firm interview in order to have a margin of error of at most 0.1 liter when constructing a 99% confidence interval
At least n teenargers must be interviewed.
n is found when M = 0.1.
We have that 
So
Rounding up
At least 832 teenargers must be interviewed.
First, calculate for the volume of the cube before each edges are cut.
V = e³
where e is the length of each sides. Substituting the known value,
V = (4/5 cm)³ = 0.512 cm³
Then, calculate for the volume of each of the small cubes cut out from the corners.
V = (1/5 cm)³ = 0.008 cm³
Since there are 8 of these small cube, we multiply the volume by 8.
8V = 8(0.008 cm³) = 0.064 cm³
Then, subtracting the volumes will give us an answer of <em>0.448 cm³</em>
NOTE THIS IS AN EXAMPLE:
Let t = time, s = ostrich, and g = giraffe.
Here's what we know:
s = g + 5 (an ostrich is 5 mph faster than a giraffe)
st = 7 (in a certain amount of time, an ostrich runs 7 miles)
gt = 6 (in the same time, a giraffe runs 6 miles)
We have a value for s, so plug it into the first equation:
(g + 5)t = 7
gt = 6
Isolate g so that we can plug that variable value into the equation:
g = 6/t
so that gives us:
(6/t + 5)t = 7
Distribute:
6 + 5t = 7
Subtract 6:
5t = 1
Divide by 5:
t = 1/5 of an hour (or 12 minutes)
Now that we have a value for time, we can plug them into our equations:
1/5 g = 6
multiply by 5:
g = 30 mph
s = 30 + 5
s = 35 mph
Check by imputing into the second equation:
st = 7
35 * 1/5 = 7
7 = 7
