Answer:
Z scores between -0.995 and 0.995 bound the middle 68% of the area under the stanrard normal curve
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean 
and standard deviation 
, the z-score 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 p-value, we get the probability that the value of the measure is greater than X.
Middle 68%
Between the 50 - (68/2) = 16th percentile and the 50 + (68/2) = 84th percentile.
16th percentile:
X when Z has a pvalue of 0.16. So X when Z = -0.995
84th percentile:
X when Z has a pvalue of 0.84. So X when Z = 0.995.
Z scores between -0.995 and 0.995 bound the middle 68% of the area under the stanrard normal curve
Answer:
The percentage of workers not wearing the helmets is 5.3 %.
Step-by-step explanation:
A safety committee randomly examined 900 construction workers during their work, and found that 48 workers were not wearing helmets. Estimate the percentage of workers who do not wear protective masks during their working time with 98% confidence
total workers = 900
Not wearing helmet = 48
Percentage which are not wearing the helmets
= 
%
Answer:
see explanation
Step-by-step explanation:
Using the trigonometric identity
sin²x + cos²x = 1
Consider the left side
2cos²A - 1 ← replace 1 by sin²A + cos²A
= 2cos²A - ( sin²A + cos²A)
= 2cos²A - sin²A - cos²A
= cos²A - sin²A = right side ⇒ verified
9514 1404 393
Answer:
Step-by-step explanation:
You know the linear pair z° and 105° are supplementary angles, so ...
z = 180 -105 = 75
The other base angle of the isosceles triangle has the same measure, 75°. __
Then x can be found either from the sum of interior angles of the triangle, or from the relation of 105° to the "remote interior angles". The first relation gives ...
75° +75° +x° = 180° ⇒ x = 180 -150 = 30
The second relation gives ...
75° +x° = 105° ⇒ x = 105 -75 = 30
__
y° is supplementary to the left-side base angle, so is ...
y = 180 -75 = 105
Of course, you could also figure y from the symmetry of the figure.
The values of x, y, z are 30, 105, 75, respectively.
