Answer:
0.33
Step-by-step explanation:
If you have the number 1 and divide it by 100, you get 1/100, 0.01, or 1% of 1. If you multiply 1/100 by 33, you get 33/100, 0.33, or 33% of 1.
Answer:
456
Step-by-step explanation:
Let X be the SATscore scored by the students
Given that X is normal (1000,200)
By converting into standard normal variate we can say that
is N(0,1)
To find the top 10% we consider the 90th percentile for z score
Z 90th percentile = 1.28

i.e. only students who scored 456 or above only should be considered.
Answer:
mmm
Step-by-step explanation:
Answer:
A sample of 179 is needed.
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
.
That is z with a pvalue of
, so Z = 1.44.
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.
A previous study found that for an average family the variance is 1.69 gallon?
This means that 
If they are using a 85% level of confidence, how large of a sample is required to estimate the mean usage of water?
A sample of n is needed, and n is found for M = 0.14. So






Rounding up
A sample of 179 is needed.
2 equations: the first one is the sum of 2 unknown numbers x and y: x + y = 72. Now the difference is 25, so x - y = 25. Solve the first equation for y: y = 72 - x. Sub that into the second equation to solve for x: x - (72 - x) = 25. x - 72 + x = 25 and 2x - 72 = 25. Therefore, 2x = 97 and x = 48.5 That's the larger of the 2 numbers; since we subtracted y from x we defined x as the larger of the 2. Just for fun, plug x in to find that y = 23.5