Betty's Bite-Size Candies are packaged in bags. The number of candies per bag is normally distributed, with a mean of 50 and a standard deviation of 3. At a quality check point, a sample bag is checked, and 12 bags contain fewer than 47 candies. How many bags were probably taken as samples?

Question

anonymous · Answer

@amistre64

anonymous · Answer

Answer choices are: 15 bags, 75 bags, 36 bags, and 24 bags.

amistre64 · Answer

what percentage of the bags would we expect to have fewer than 47 in them?

anonymous · Answer

I don't even remember what formula to use.

amistre64 · Answer

z formula might be useful

amistre64 · Answer

otherwise,  47 is 3 (1 sd) under the mean of 50

anonymous · Answer

Yes I got that part.

anonymous · Answer

What's after that?

amistre64 · Answer

well, a z table or empirical rule might be useful.

do you recall the approximate percentage that is 1 sd from the mean?

anonymous · Answer

25?

amistre64 · Answer

|dw:1427249230808:dw|

anonymous · Answer

How did you find 34? and what's the scriggle?

amistre64 · Answer

50% - 34% = 16% of the bags we would expect to have less than 47

anonymous · Answer

Where did 34 come in? Is that the rule?

amistre64 · Answer

alpha is the scribble.  i remember the empirical rule that says between -1 and 1 sd from the mean there is approx 68% of the data, so 34% to the left and 34% to the right

amistre64 · Answer

34% + alpha = 50% of distribution

anonymous · Answer

Oh yeah that's right. I remember that now!

amistre64 · Answer

so we expect about 16% if the samples to have less than 47 in them

well, 12 is 16% of what value?

anonymous · Answer

75?

anonymous · Answer

12/.16=75

amistre64 · Answer

12/75 = .16 so id have to agree with that :)

amistre64 · Answer

gotta drive a kid to work, so have fun :)

anonymous · Answer

thanks

zarkon · Answer

"the number of candies is normally distributed"...must be a lot of broken pieces in the bag 

Weird problem