Answer:
Step-by-step explanation:
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".
Let X the random variable that represent the Student scores on exams given by a certain instructor, we know that X have the following distribution:

The sampling distribution for the sample mean is given by:
The deduction is explained below we have this:
Since the variance for each individual observation is
then:
And then for this special case:
We are interested on this probability:
And we have already found the probability distribution for the sample mean on part a. So on this case we can use the z score formula given by:
Applying this we have the following result:
And using the normal standard distribution, Excel or a calculator we find this:
Answer:
original number is 18.07
Step-by-step explanation:
Let the original number be x
x - 17% of x = 15
x* (1 - 0.17) = 15
x * 0.83 = 15
x = 15/0.83
x = 18.072289156
Or if your wording meant 17% of a number is 15 then:
x * 17% = 15
x *0.17 = 15
x = 15/0.17 = 88.23529...
but I think you meant "decreased by 17%" so I choose x = 18.07
Answer:
(D)
Step-by-step explanation:
A.
which is a negative number, thus Option A is incorrect.
B.
which is a negative number, thus Option B is incorrect.
C.
which is a negative number, thus option C is incorrect.
D.
which is a positive number, thus option D is correct.
Answer:
75 minutes
50 minutes
Number of minutes to finish labelling = Total number of books labelled / Time taken to label them (speed of labelling)
Step-by-step explanation:
Complete question below:
Clare volunteers at a local library during the summer. Her work includes putting labels on 750 books.
How many minutes will she need to finish labeling all books if If she takes no breaks and labels:
a. 10 books a minute
b. 15 books a minute
Suppose Clare labels the books at a constant speed of books per minute. Write an equation that represents the relationship between her labeling speed and the number of minutes it would take her to finish labeling
Solution
a. 10 books a minute
Number of minutes to finish labelling all books at 10 books per minute = Total books / books labelled per minute
= 750 / 10
= 75 minutes
Number of minutes to finish labelling all books at 10 books per minute = 75 minutes
b. 15 books a minute
Number of minutes to finish labelling all books at 15 books per minute = Total books / books labelled per minute
= 750 / 15
= 50 minutes
Number of minutes to finish labelling all books at 15 books per minute = 50 minutes
c. The relationship between her labeling speed and the number of minutes is Total number of books labeled ÷ Time taken to label them
Number of minutes to finish labelling = Total number of books labelled / Time taken to label them (speed of labelling)