Question

he brain volumes ​(cm cubedcm3​) of 20 brains have a mean of 1103.81103.8 cm cubedcm3 and a standard deviation of 121.9121.9 cm cubedcm3. Use the given standard deviation and the range rule of thumb to identify the limits separating values that are significantly low or significantly high. For such​ data, would a brain volume of 1367.61367.6 cm cubedcm3 be significantly​ high?

Answer 1

Answer: We can say that brain volume of 1367.6 cubic cm would be significantly high.

Explanation:

Since we have given that

n = 20 brains

Mean = 1103.8 cubic. cm

Standard deviation = 121.9 cubic. cm

According to range rule of thumb, the usual values must lie within 2 standard values from the mean.

So, it becomes,

`\bar{x}-2\sigma\\\\=1103.8-2* 121.9\\\\=1103.8-243.8\\\\=860`

and

`\bar{x}+2\sigma\\\\=1103.8+2* 121.9\\\\=1103.8+243.8\\\\=1225.7`

We can see that 1376.6 does not lie within (860,1225.7).

So, we can say that brain volume of 1367.6 cubic cm would be significantly high.