Answer:
a.1.90 years
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.
In this question:

So

So the correct answer is:
a.1.90 years
You could understand the ration as parts: the total number of parts was 3+7=10.
So girls were 3/10 parts and boys 7/10 parts. The difference was 7-3=4 parts. this difference is equal to 360, so each part is 90 (4*90 =360).
so girls are "3 parts" and each part is 90, then the number of girls is 3*90=270.
Answer: the amount a person pays for gas compared with the number of gallons purchased
Step-by-step explanation:
1000*200=200000
This will be your answer
thanks
Answer:
125
Step-by-step explanation:
Well if 10 x 50 is 500 (just to show how you get doesn't affect problem) you would simply divide by 4 thus, you get 125 (edit: sorry if this is wrong I'm in my first year of middle lol)