Suppose that IQ scores have a bell-shaped distribution with a mean of 98
and a standard deviation of 13
. Using the empirical rule, what percentage of IQ scores are between 72
and 124
?



Answer :

Answer:

95%

Step-by-step explanation:

The empirical rule(68–95–99.7 rule) states that after 1 standard deviation, 68% of the data falls within that range. Subsequent standard deviations will result in 95% and then 99.7%.  We must find how many standard deviations occurred in the range given to figure out what percentage of data falls within that range.

Solving:

[tex]\subsection*{}\[\text{Mean } (\mu) = 98\]\[\text{Standard deviation } (\sigma) = 13\][/tex]

[tex]\[\text{Number of standard deviations from 72 to the mean} = \frac{98 - 72}{13} = \frac{26}{13} = \boxed{2}\]\[\text{Number of standard deviations from 124 to the mean} = \frac{124 - 98}{13} = \frac{26}{13} = \boxed{2}\][/tex]

[tex]\begin{itemize} \item About 68\% of the data falls within 1 standard deviation of the mean. \item About 95\% of the data falls within 2 standard deviations of the mean. \item About 99.7\% of the data falls within 3 standard deviations of the mean.\end{itemize}[/tex]

Since both 72 and 124 are 2 standard deviations away from the mean, the percentage of IQ scores between 72 and 124 is approximately 95%.