In monitoring lead in the air after the explosion at the battery factory, it is found that the amounts of lead over a 7 day period had a standard error of 1.91. Find the margin of error that corresponds to a 95% confidence interval. (Round to 2 decimal places)

Step-by-step explanation:

-Given that

-We determine the z-value corresponding to the 95% confidence level:

-The margin of error is the degree of error from the real value and is calculated as follows:

Hence, the margin of error is

if you are saying purchasing 3 social media ads and one newspaper ad counts as one purchase then there are:

6 purchases

if you are asking how many of each then:

18 social media ads

6 newspaper ads

i think it is 18

step-by-step explanation: