D. would be the right answer mate
Answer:
center = 98.6, variability = 0.08
Step-by-step explanation:
The Central Limit Theorem estabilishes that, for a random variable X, with mean
and standard deviation
, the sample means with size n of at least 30 can be approximated to a normal distribution with mean
and standard deviation 
The center is the mean.
So 
The standard deviation of the sample of 50 adults is the variability, so

So the correct answer is:
center = 98.6, variability = 0.08
What type of data? Usually, mean is the best representative.
15 - 9 = 6 6÷3=2 X=2
You do the inverse operation
Answer:
- P(x < 84) = 0.3085 or approximately 31%
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<em>Hello to you from Brainly team!</em>
<h3>Given</h3>
- Mean grade μ = 86,
- Standard deviation σ = 4,
- Grade limit x = 84.
<h3>To find </h3>
- Probability of that a randomly selected grade is less than 84 or P(x < 84).
<h3>Solution</h3>
Find z-score using relevant equation:
Substitute values and calculate:
Using the z-score table find the corresponding P- value.
- P(x < 84) = 0.30854 or approximately 31%