Question

A set of 50 data values has a mean of 22 and a variance of 16.
I. Find the standard score (z) for a data value = 14.
II. Find the probability of a data value < 14.

Answer 1

do you recall the formula for the z?

Answer 2

no I donot know

Answer 3

how have you been calculating the z score then?

Answer 4

thats just it , I havent because I dont understand this type of problem

Answer 5

a zscore takes the given data and conforms it to a normal distribution with a mean of 0 and a variance of 1

Answer 6

in order to get the mean from 22 to 0; we have to subtract 22 from it; and all the pointes related to the distribution for starters

Answer 7

16/16 = 1 so all the variances are compacted into this; but we usually determine the zscore with a standard deviation (sd); sd = sqrt(variance) so lets divide all the points associated with this thing by sqrt(16)

the formula is\[z=\frac{x-mean}{\sqrt{var}}\]

Answer 8

so for the first part subtract , and for the second part use this formula rite ?

Answer 9

the first part is using the formula to find the z score; the second uses that zscore to determine probability with

Answer 10

\[z=\frac{14-22}{\sqrt{16}}\]

Answer 11

would you happen to have a ti83 or some similar calculator? for this

Answer 12

no I dont

Answer 13

then we will have to stick with using formulas and the ztable in the back of the book for this

Answer 14

ok

Answer 15

you do have a "back of the book" right?

Answer 16

so for the 1st part -2 wud be the answer rite ?

Answer 17

correct

Answer 18

yes

Answer 19

do we have options for part2 or is it a fill in? becasue there are 2 ways we can get the answer, one is approximate and the other mroe exacting

Answer 20

a fill in

Answer 21

the empirical data rule of thumb is that 47.5% of the data falls between the mean and 2 sds from the mean; and that would be an approximate fill in

Answer 22

ok thanks