At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.
change the pounds of force to # of std deviations above or below the mean.
? what i dont get what ur saying
200 is the mean (the average) and the standard deviation is 3
so make it 3lbs = standard deviation 200
so what is 194 ? it is two standard deviations below the mean (i.e. 200 - 2*3)
its 194 and 206
yes, and 194 is 2 std dev below the mean what is 206 ?
above the mean is 206
so B is the one thats not true
yes 206 is above (i.e. bigger than) 200 but by how much ? by 6 lbs but what is 6 lbs in standard deviations? i.e. how many std dev is 6 ?
itll be 2 going up cause the standard deviation is 3
yes, 206 is 2 std dev above the mean so lets look at the choices. this is the easiest one to figure out About 500 springs could withstand 200 lbs or more of force.
if the whole "bell curve" is 1000 springs and 1/2 of them are "above the mean" (i.e stronger than 200 lbs) how many is that ? in other words, what is 1/2 of 1000 ?
500 is half of 1000
About 500 springs could withstand 200 lbs or more of force. is true.
so that cant be the answer were looking for which is not true
should i find half of 950
half of 950 is 475
choice B is saying 950 are between -2 and +2 standard deviations according to the bell curve posted up above, do you see 95% should be between -2 and +2?
so to check 950 are between -2 and +2 standard deviations what is 95% of 1000 ?
yea and its still enough to with stand it
in case it's not obvious, we have 1000 springs and we measure how strong they are and sort them by strength. If we do that, 95% of them will be between -2 and +2 std dev of the mean. what is 95% of 1000 ?
would i do 1000/.95
95 % of 1000 means 0.95 * 1000 you get 950 (notice if you write 950/1000 and simplify you get 0.95 = 95%)
in other words, choice B is correct 95% (of the 1000 springs) are between -2 and +2
so choice B and C are correct so cross those out
now let's look at About 25 springs could withstand more than 206 lbs of force. more than 206 means more than +2 std dev|dw:1442260036131:dw|
do you see springs stronger than 206 are in the right region above +2 that region is 2.5% of the 1000 what is 2.5% of 1000 ?
answer is D thanks
you could use a calculator. but 2.5% of 1000 is 0.025*100 = 25 so D is correct so by process of elimination A is wrong but if we look at choice A About 15 springs could withstand less than 194 lbs of force the number of springs less than -2 std dev should be 2.5% of 1000 (which we know is 25) 15 is too small, it should be 25 so that shows choice A is wrong.
so the answer i should choose is D
no, the answer is not D. read what I posted up above.
oh i see it so its A