Question

The amount of chocolate candies are normally distributed with a mean of 25 and a standard deviation of 3. Approximately what precent of the bags contain between 19 and 31 candies?? @phi @SolomonZelman @campbell_st @mathstudent55 @iambatman @uri @sauravshakya

Answer 1

the first step is change 19 to the number of standard deviations below the mean (of 25)

to do that, first find the difference between 19 and 25
can you do that ?

Answer 2

Should I just subtract 19 and 25? @phi
Ps: Thank you in advance for your help!

Answer 3

yes, (and we always subtract the mean)

Answer 4

So, 6?

Answer 5

almost. 19-25

Answer 6

Ahh, -6 then!

Answer 7

yes, the -6 means we are to the left of the mean

next, we change that into the number of standard deviations. (i.e divide the the size of the standard deviation)

Answer 8

So, 3/-6?

Answer 9

you divide by the standard deviation (=3).

you did it upside down

Answer 10

in other words, if 3 units is one standard deviation then 6 units will be 2 standard dev.
i.e. 6/3 = 2

Answer 11

So since its a negative 6 divided by a positive we would get -2

Answer 12

yes

if we sketch this on a "bell curve" we have