Answer:
And using the normal standard table or excel we find the probability:

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".
Solution to the problem
Let X the random variable that represent the avergae number of weeks an individual is unemployed of a population, and for this case we know the distribution for X is given by:
Where
and
Since the distribution for X is normal then, the distribution for the sample mean
is given by:
We select a sample of n =50 people. And we want to find the following probability
And using the normal standard table or excel we find the probability:

Answer:
Speed of the river =
km per hour
Step-by-step explanation:
Speed of the boat in still water = 4 km per hour
Let the speed of the river = v km per hour
Speed of the boat upstream = (4 - v) km per hour
Time taken to cover 6 km = 
=
hours
Speed of the boat downstream = (4 + v) km per hour
Time taken to cover 12 km =
hours
Since, time taken by the boat in both the cases is same,

6(4 + v) = 12(4 - v)
24 + 6v = 48 - 12v
12v + 6v = 48 - 24
18v = 24
v = 
v =
km per hour
Answer:
its A
Step-by-step explanation:
Hey mate ,
here is your answer
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The average between any two rational numbers is also rational.
(7.7 + 7.9)/2 = 7.8
7.8 is rational because it can be written as a fraction with integer numerator and denominator (39/5) and it is also a terminating decimal.