Question

Statistics Algebra 2 help !

Answer 1

The grades on the last science exam had a mean of 89%. Assume the population of grades on science exams is known to be distributed normally, with a standard deviation of 14%. Approximately what percent of students earn a score between 75% and 89%?

Answer 2

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Answer 3

hmm, id have to know what your material has covered so far

Answer 4

and what you have to work the problem with

Answer 5

it feels to me like an empirical rule approximation tho ...

Answer 6

it is indeed, but im not sure how to use it

Answer 7

well, determine how many deviations are between the mean and your end points

Answer 8

what is our mean?

Answer 9

89%

Answer 10

and what is our left end point?

Answer 11

75%

Answer 12

with a standard deviation of 14%

Answer 13

so, the difference between them is:

what is 89-75?

Answer 14

14

Answer 15

which is exactly 1 standard deviation to the left of the mean. right?

Answer 16

if we calculate the same with the other end point .. well, 89 to 89 is a difference of 0, so no standard deviations are to the right of the mean.

what are your thoughts?

Answer 17

I didnt get it, can you elaborate more?

Answer 18

the only thing left to elaborate is what does the empirical rule state?

it may be called something else in your material tho.

Answer 19

and do we have options to choose from?

Answer 20

68% will fall within the first standard deviation, 95%, the first two and 99.7 first three

Answer 21

the options are:
38.5%
15.7%
50%
34.1%

Answer 22

thats the rule yes, but it is better stated:

within +- 1sd from the mean falls 68% of the data.

68/2 = 34

so 34% to the left (-1 sd), and 34% to the right (+1 sd)

we know we are 1sd to the left, and 0 to the right ...

what does that tell us?