16) Assuming that the number of shoppers who buy a packet of crackers is approximately normal with a mean of 20 and standard dev
1 answer:
Answer:
2.28% probability that at least 28 of the next 100 shoppers who sample the crackers will buy a pack
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean and standard deviation
, the zscore of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:
What is the approximate probability that at least 28 of the next 100 shoppers who sample the crackers will buy a pack?
This probability is 1 subtracted by the pvalue of Z when X = 28. So
has a pvalue of 0.9772
1 - 0.9772 = 0.0228
2.28% probability that at least 28 of the next 100 shoppers who sample the crackers will buy a pack
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You can show that by constructing a triangle.
Take two points, O(0, 0) and A(1, 0), and let B be the point on the unit circle such that the angle between the line segments OA and OB is radians.
Since both A and B lie on the circle, the line segments OA and OB both have length 1 (same as the circle's radius). We finish constructing the triangle by connect A and B.
Since OB and OA have the same length, triangle OAB is isosceles, but more than that, it's also equilateral. Why? Because the interior angles of any triangle always add to radians. We know one of the angles is
radians, which leaves a contribution of
radians between the remaining angles A and B. Angles A and B must be congruent (because OAB is isosceles), which means they also have measure
radians.
Next, draw an altitude of the triangle through point B, and label the point where it meets the "base" OA, C. Since OAB is equilateral, the altitude BC is also a perpendicular bisector. That means OC has length , and by definition of
we have
Answer:
As θ increases, the value of cos θ decreases
Step-by-step explanation:
As as θ increases, the value of cos θ decreases from 1 to -1 in the first two quadrants ( between 0 and 180 degrees). Cos(0) = 1, cos(90) = 0, cos(180) = -1.
On the other hand, as θ increases from 180 to 360 degrees (last two quadrants) the value of cos θ increases from -1 to 1.
Check the attachment below:
