Rewrite <span>2cos x + 1 = 0 as:
2 cos x = -1, and then cos x = -1/2
x must be in Quadrant II or Quadrant III, since the adj. side is negative.
Note that the angle 120 has adj. side -1 and hyp 2. So 120 degrees is one solution.
Now what about a possible 2nd solution, to be found in Quadrant III? That would be -120 degrees, which has the same terminal line as does 240 degrees.
No soap.
So, the solution is 120 degrees.</span>
Answer:
He must survey 123 adults.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of
, and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the z-score that has a p-value of
.
The margin of error is:

Assume that a recent survey suggests that about 87% of adults have heard of the brand.
This means that 
90% confidence level
So
, z is the value of Z that has a p-value of
, so
.
How many adults must he survey in order to be 90% confident that his estimate is within five percentage points of the true population percentage?
This is n for which M = 0.05. So






Rounding up:
He must survey 123 adults.
this is a function becuase it passes the verticle line test (no 2 points are above each other).
Answer:
14 hours
Step-by-step explanation:
Let's call the task 3x
The older bro does twice as younger so it would be 2x long and younger brother work x long
Since the totsl of work is 3x = 21 x woul be 21÷3 = 7
the older brother must work 2 × 7 = 14 hours long
Answer:
We see that the p value is lower than the significance level given of 0.01 so then we can conclude that the true mean for the nicotine content is significantly higher than 40 mg
Step-by-step explanation:
Information provided
represent the average nicotine content
represent the sample standard deviation
sample size
represent the value to check
represent the significance level for the hypothesis test.
t would represent the statistic
represent the p value for the test
System of hypothesis
We want to verify if the nicotine content of the cigarettes exceeds 40 mg , the system of hypothesis are:
Null hypothesis:
Alternative hypothesis:
The statistic for this case would be:
(1)
And replcing we got:
The degrees of freedom are:
The p value would be:
We see that the p value is lower than the significance level given of 0.01 so then we can conclude that the true mean for the nicotine content is significantly higher than 40 mg