Jeffery conducted a survey in his school and found that 30 of the 50 eighth grade students' favorite subject is mathematics. based on the results, jeffery concluded that out of the 200 students in his school, 120 students' favorite subject is mathematics.

select the statement that is true about jeffery's conclusion.

a.

jeffery's conclusion is not valid because the sample was biased since only 200 students were surveyed.

b.

jeffery's conclusion is valid because the sample was random since all of the students were eighth grade students.

c.

jeffery's conclusion is valid because the sample was random.

d.

jeffery's conclusion is not valid because the sample was biased since all of the students were eighth grade students.

The correct answer is:

D) Jeffery's conclusion is not valid because the sample was biased since all of the students were eighth grade students.

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!

step-by-step explanation:

i believe its "c" because all of the other options include a but it could be d because there is a way of financing with cash at certain places but its uncommon.