Answer:
(a) The sample variance is 16.51
(a) The sample standard deviation is 4.06
Step-by-step explanation:
Given

Solving (a); The sample variance.
First, calculate the class midpoints.
This is the mean of the intervals.
i.e.





So, the table becomes:

Next, calculate the mean




Next, the sample variance is:

So, we have:



The sample standard deviation is:



It'd be 9.096491 hope that helps.
70+75+80+90+100=415
415/5=83
<span>After the lowest grade is dropped, Janet's average would be an 83%</span>
Answer:
it would be in the fourth quadrant, directly underneath where it is now. the base would be c and d
The answer is Johnny. You can conclude from the first sentence of your question. It is stating that Johnny's mother has three children. Johnny is included in the three children. So, the third child's name was Johnny!
Thank you! :D