Answer: c. z = 1.35; Reject the null hypothesis
Step-by-step explanation:
Let 
be the average life expectancy of its batteries.
As per given , we have
Null hypothesis : 
Alternative hypothesis : 
Since 
is right-tailed and population standard deviation is also known, so we perform right-tailed z-test.
Test statistic : 
where, n= sample size
= sample mean
= Population mean
=population standard deviation
For 
, we have
Critical one-tailed test value for 0.10 significance level :
Decision : Since critical z value (1.28) < test statistic (1.35), so we reject the null hypothesis .
[When critical value is less than the test statistic value , we reject the null hypothesis .]
I'm assuming you're referring to problem 6. You are asked to find the number of x intercepts or roots, which is another term for "zero". I prefer the term root or x intercept as "zero" seems misleading. Anyways, all we do is count the number of times the graph crosses the x axis. This happens 4 times as shown in the attached image below. I have marked these points in red. The graph can directly cross over the x axis, or it can touch the x axis and then bounce back. Either way, it is considered an x intercept.
<h3>Answer: there are 4 x intercepts (or 4 roots)</h3>
So just divide 100 by 25 which equals 4 then divide 120 by 30 which also equals to 4 and if the rest equal 4 then its proportional (1)
And then same for 2 and 3 just divided the bottom by the top and if they all get the same answer they are proportion and if one is not the same then it’s not
For the grids if the dots are line diagonally straight and it starts at the 0 then it’s proportional if not then it’s not
Hope this helps :)
Answer:
21-7x
Step-by-step explanation: gather like terms
25-4=21 -9x+2x=-7x
