Question

Help!!!
The number of books borrowed from a library each week follows a normal distribution. When a sample is taken for several weeks, the mean is found to be 190 and the standard deviation is 30.
There is a ??? % chance that more than 250 books were borrowed in a week.

Answer 1

68% - 1
95% -2
99.7% - 3

Answer 2

how many standard deviation is 250 from 190?

Answer 3

190 + 30n = 250, what is n?

Answer 4

n=2

Answer 5

without any other information given, how do use this?

Answer 6

so 95%
mean+SD(n)=250

Answer 7

so it is 2 standard deviations

Answer 8

thats it?

Answer 9

the probabilty of MORE than 250

we whould now by some approximation rule that 95% of the data is within 2sd of the mean

this gives us 5% to split between the tails. 2.5% each

MORE than 250 is only 1 tail .... so it only represent 2.5% of the data

Answer 10

your options, im assuming that what they are, do not line up with the question being asked

Answer 11

or if they are just a reminder of the rule, then we have solved it

Answer 12

oh ok i need to find the chance of more than 250