According to a report from a business intelligence company, smartphone owners are using an average of 18 apps per month. Assume that number of apps used per month by smartphone owners is normally distributed and that the standard deviation is 7. Complete parts (a) through (d) below.
a. If you select a random sample of 36 smartphone owners, what is the probability that the sample mean is between 17.5 and 18.5?
nothing (Round to three decimal places as needed.)

step-by-step explanation:

the system of inequity is

step-by-step explanation:

from the given graph it is noticed that we have two related lines. one is solid and another is dashed.

if a line passing through two points, then the equation of line is

the solid line passing through the points (0,4) and (4,0).

the related equation of solid line is .

similarly, find the related equation of dashed line. the dashed liune passing through the points (0,0) and (3,1).

the related equation of dashed line is

from the given graph it is noticed that the point (0,1) lies on the shaded region, therefore the point (0,1) must be satisfied by the related equations.

check the related equations by the point (0,1).

this statement is true if the sign of inequality is < instead of equality. since it is an solid line therefore the sign of inequality will be . the required inequality is

similarly, check the second related equation.

it is a dashed line, so this statement is true if the sign of inequality is > . the required inequality is

what is the original number? you forgot to add it.

answer: (-6,3)

step-by-step explanation: