Question

Hi, I was wondering if someone could help me out with this. I know I need to use the empirical rule but other than that, I'm pretty lost.

Scores of an IQ test have a bell-shaped distribution with a mean of 100 and a standard deviation of 18.

A. What percentage of people has an IQ score between 46 and 154?

B. What percentage of people has an IQ score less than 64 or greater than 136?

C. What percentage of people has an IQ score greater than 118?

Thanks in advance!!

Answer 1

What do you remember of the empirical rule?

Answer 2

I know it's for normal distribution and determined with the mean and the standard deviation. I'm just not positive about how to figure out the answers.

Answer 3

check out this page

http://www.oswego.edu/~srp/stats/6895997.htm

Answer 4

tell me if that looks familiar or not

Answer 5

It looks familiar from my textbook but I just can't wrap my head around the concept and how to figure it out.

Answer 6

the mean is 100

the std dev is 18

Answer 7

what IQ score is 1 std dev above the mean?

Answer 8

118?

Answer 9

what's 1 std dev below the mean

Answer 10

82?

Answer 11

so 68% of the population has an IQ score between 82 and 118

Answer 12

according to the empirical rule (this is an approximation)

Answer 13

between what two scores does 95% of the population lie?