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
=
%
20 + 4 + 3/10 + 5/100 + 7/1000
Using the normal distribution, it is found that:
a) The pilot is at the 72th percentile.
b) 19.13% of pilots are unable to fly.
<h3>Normal Probability Distribution</h3>
The z-score of a measure X of a normally distributed variable with mean
and standard deviation
is given by:

- The z-score measures how many standard deviations the measure is above or below the mean.
- Looking at the z-score table, the p-value associated with this z-score is found, which is the percentile of X.
The mean and the standard deviation are given, respectively, by:
.
Item a:
The percentile is the <u>p-value of Z when X = 74.2</u>, hence:


Z = 0.59
Z = 0.59 has a p-value of 0.7224.
72th percentile.
Item b:
The proportion that is able to fly is the <u>p-value of Z when X = 78 subtracted by the p-value of Z when X = 70</u>, hence:
X = 78:


Z = 2
Z = 2 has a p-value of 0.9772.
X = 70:


Z = -0.96
Z = -0.96 has a p-value of 0.1685.
0.9772 - 0.1685 = 0.8087 = 80.87%.
Hence the percentage that is unable to fly is:
100 - 80.87 = 19.13%.
More can be learned about the normal distribution at brainly.com/question/4079902
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