betty's bite-size candies are packaged in bags. The number of candies per ba is normally distributed, with a mean of 50 candies and a standard deviation of 3. At a quality control checkpoint, a sample of bags is checked, and 4 bags contain fewer than 47 candies. How many bags were probably taken as samples?

Question

amistre64 · Answer

hmmm, im wanting to say this involves a sqrt(n)

amistre64 · Answer

$$z=\frac{x-\bar x}{sd}\sqrt{n}$$
$$\frac{z(sd)}{x-\bar x}=\sqrt{n}$$
$$(\frac{z(sd)}{x-\bar x})^2=n$$
but im not too sure if thats a good thought yet or not

amistre64 · Answer

there are 47 is wiithin 1 sd from the mean

which is about what we would expect 16% of the sample to have

since there are 4 bags .... then 100 is to 16 as 25 is to 4

amistre64 · Answer

might be right :)  any ideas?

amistre64 · Answer

50 - 3 = 47, is 1 sd from the mean.  1 sd from the mean as about 34% on each side

50 - 34 = 16, so 16 out of 100 are expected to have less than a 47 count.

4  is 16% of what number?

amistre64 · Answer

$$\frac{16}{100}=\frac{4}{n}$$
$$\frac{4}{100}=\frac{1}{n}$$
$$\frac{100}{4}=n=25$$

anonymous · Answer

can you help me in another question

anonymous · Answer

please

amistre64 · Answer

dunno, my smarts are fairly limited to this question and something about marginal tax flows in algeria