In each part, find the area under the standard normal curve that lies between the specified z-score, sketch a standard normal curve, and shade the area of interest.

a. minus1 and 1
b. minus2 and 2
c. minus3 and 3

a)

b)

c)

The results are on the fogure attached.

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

Part a

For this case we want to find this probability:

And we can find this probability with this difference:

And if we find the probability using the normal standard distribution or excel we got:

Part b

For this case we want to find this probability:

And we can find this probability with this difference:

And if we find the probability using the normal standard distribution or excel we got:

Part c

For this case we want to find this probability:

And we can find this probability with this difference:

And if we find the probability using the normal standard distribution or excel we got:

1/3

step-by-step explanation:

to find this, you can divide 12 by 4 which is 3 or you can multiply 4 until you reach 12 (4x3=12). both should give you 3, meaning theres three times less bananas than there are oranges.