Question

SHOW THE PROPORTION YOU ARE SETTING UP.Four out of 10 adults in a certain city buy their drugs at large drug stores. If this city has 34,000 adults, how many of these adults would you expectto buy their drugs at large drug stores?

Answer 1

You know that 4 out of 10 adults buy their drugs at large drug stores. To calculate the value of the proportion you have to divide 4 by 10

$\begin{gathered} p=\frac{4}{10} \\ p=0.4 \end{gathered}$

The city has n=34,000 adults, to determine the expected number of adults that buy at large drugstores, you have to multiply the total number of adults by the proportion:

$E(X)=np$

n=34,000 and p=0.4

$\begin{gathered} E(X)=34000\cdot0.4 \\ E(X)=13600 \end{gathered}$

Out of the 34,000 you could expect 13,600 adults to buy at large drug stores.