You do 18.6 ÷ 3 and that equals 6.2
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 .]
Answer:
4pi + 8 km
Step-by-step explanation:
the circumference of teh circle is d*pi = 8pi. since this is a semicircle the circumference is 4pi. then the perimeter is 4pi + 8
Answer:

Step-by-step explanation:
√a^4 is the same as:
√a × √a × √a × √a
group them as 2 pairs of
(√a × √a) × (√a × √a)
which makes
a × a
which is the same as 
Answer:
C. -2.5 - 6.5n
Step-by-step explanation:
i just think thats the answer