<h2><u>
Answer with explanation</u>
:</h2>
Let
be the average life of light bulbs.
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.
Formula for Test statistic : 
where, n= sample size
= sample mean
= Population mean
=population standard deviation
For
, we have

Using z-value table , Critical one-tailed test value for 0.06 significance level :

Decision : Since critical z value (1.5548) < test statistic (1.6180), so we reject the null hypothesis .
[We reject the null hypothesis when critical value is less than the test statistic value .]
Conclusion : We have enough evidence at 0.06 significance level to support the claim that the new filament yields a longer bulb life
Answer:
7 hours
Step-by-step explanation:
We are given that
At sunset, the temperature=-5 degrees Fahrenheit
Each hour, temperature falling=2degrees Fahrenheit
We have to find time taken to reach the temperature -19° F.
Let x be the time time taken to reach the temperature -19° F
According to question

Where we taking 2 negative because temperature decreases.





Hence, it will take 7 hours for the temperature to reach -19° F.
Answer:
B
Step-by-Step Explanation:
if you do a <u>Percent Proportion</u> you will get:
_1__ = _0.1_ 0.1x10=1
1000 100