Answer:
1.172 dollars per pound
Step-by-step explanation:
Given : A pet supply store sells a 20-pound bag of dog food $23.44.
To Find :Find the unit price.
Solution :
Cost of 20-pound bag of food = $23.44
So, Cost of 1-pound bag of food =
=
For unit price we should divide the cost by no. of pounds
So, the error is you have divided the no. of pounds by cost
Hence the unit price is 1.172 dollars per pound
Answer:
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 grades of a population, and for this case we know the distribution for X is given by:
For this case we have two conditions given:
or equivalently
And the best way to solve this problem is using the normal standard distribution and the z score given by:
So we can find a value from the normal standard distribution that accumulates 0.1 and 0.9 of the area in the left, for this case the two values are:
We can verify that P(Z<-1.28) =0.1[/tex] and P(Z<1.28) =0.9[/tex]
And then using the z score we have the following formulas:
(1)
(2)
If we add equations (1) and (2) we got:
We can multiply both sides of the equation by and we got:
And then we can find the standard deviation for example from equation (1) and we got:
So then the answer would be: