8b = 24 8 8 X = 3x8=24
2 answers:
You might be interested in
Answer:
a)
b)
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Part a
Let X the random variable that represent the weights of a population, and for this case we know the distribution for X is given by:
Where and
We are interested on this probability
And the best way to solve this problem is using the normal standard distribution and the z score given by:
If we apply this formula to our probability we got this:
And we can find this probability like this:
And in order to find these probabilities we can find tables for the normal standard distribution, excel or a calculator.
Part b
For this case we select a sample size of n =32. Since the distribution for X is normal then the distribution for the sample mean is given by:
And the new z score would be:
Answer:
(a) The probability distribution is valid.
(b) The probability that x = 30 is 0.30.
Step-by-step explanation:
The probability distribution of the random variable <em>X</em> is:
<em> x</em>: 20 | 25 | 30 | 35
f (<em>x</em>): 0.20 | 0.15 | 0.30 | 0.35
(a)
The properties of a probability distribution are:
- 0 ≤ P (X) ≤ 1
- ∑ P (X) = 1
All the probability value are more than 0 and less than 1.
Compute the sum of all the probabilities as follows:
The sum of all probabilities is 1.
Thus, the probability distribution is valid.
(b)
Consider the probability distribution table.
The probability of <em>X</em> = 30 is,
P (X = 30) = 0.30.
Thus, the probability that x = 30 is 0.30.