<u>Answer:</u>
cos B = 0.4706
<u>Step-by-step explanation:</u>
The cosine of an angle in a right-angled triangle is the ratio of its adjacent side and the hypotenuse, so:

The expected value, in percent, is 0.2*15+0.4*20+0.3*30+0.1*35=23.5%.
Answer:
The answer to this question is D: None of the above
Step-by-step explanation:
From the example given in the question, this is a bad way of data sampling. The example in the question is a typical Voluntary response sample. In this type of sampling, the researcher creates a request as the case may be in the example through television, and ask for members of a population to join. Thus people then choose to be part of the sample or not. In this type of sampling, the respondents tend to have alike opinion in contrast to the rest of the population. This therefore makes voluntary response sample kind of bias.
Answer: standard deviation = 8
This is because mu = 75 is the mean, which is at the very exact center of this distribution. One space to the right is 83, which is 83-75 = 8 units away from the center. This distance is exactly one standard deviation. We can say "83 is one standard deviation larger than 75".
Or you could note the distance from 67 to 75 is also 8, because 75-67 = 8. Each tickmark represents stepping one standard deviation in distance.