Question

)Margie takes a random sample of 30 students in her seventh-grade class and finds that 75% of the sample prefers the color blue over the color red. There are 125 students in the seventh grade. Based on the sample proportion, about how many students in the seventh grade would be expected to prefer blue over red?

30
75
94
125

Answer 1

@Michele_Laino

Answer 2

hint:
75% means that every 100 students, only 75 prefer blue color over red color

Answer 3

Okay, so the 30 students is a bit of a misleading fact. It doesn't really matter for a problem like this. All you need to know is the proportion.

Answer 4

so its 75?

Answer 5

So we have ~75% of students liking the color blue. Can you convert this to decimal or fractions?

Answer 6

.75

Answer 7

75/100

Answer 8

Good. That's going to be about the proportion of students liking the color blue. Now, we want to see, out of 125 students, about how many will like the color blue?

Answer 9

no, since we have 125 students, so we have to solve this proportion:
125: x = 100: 75
where x is the requested number
what is x?

Answer 10

30?

Answer 11

both methods are fine

Answer 12

To do this, we want the proprortion to 125 to equal .75

so

75/100 = X/125

Do you think you can solve it from there?

Answer 13

thanks! @amistre64

Answer 14

is it 30?

Answer 15

The ncie thing about multiple choice questions is you can guess and check. Why don't you try plugging 30 in for x and seeing if it equals .75?

Answer 16

in order to solve that proportion, we have to apply the fundamental property of proportions, namely:
100* x= 75*125
please divide both sides by 100 and you will get your answer

Answer 17

125..? i think cuz 125/100 is 1.25

Answer 18

then multiply 1.25 by 75

Answer 19

94

Answer 20

that's right!

Answer 21

thx again Michele

Answer 22

thanks! @ashley_13

Answer 23

Do you want to go over some of the reasoning again? Or do you think you could do this type of problem on your own?

Answer 24

i culd do it on my own ^.^ thx