Which ratios form a proportion? a. 9/45,8/40 b. 9/22,14/28 c. 8/12,12! 15 d.8/12,12/21

Choice A) 9/45 and 8/40

If you divide both top and bottom of 9/45 by the GCF 9, you get 1/5

If you divide top and bottom of 8/40 by the GCF 8, you also get 1/5

So the original fractions must be the same

Another way to check is to use a calculator and see that 9/45 = 0.2 and 8/40 = 0.2, so 9/45 = 8/40

Or you can subtract the fractions and you should end up with 0, so, 9/45 - 8/40 = 0

You can also set up a proportion and cross multiply

9/45 = 8/40

9*40 = 45*8

360 = 360

The last equation is true, so the first equation must be true

answer: #1 ads up by 8 and i don't know #2

1. sometimes

2.   never

3   .08c = 7.50+.05c   250 pages

step-by-step explanation:

1.   sometimes

the theoretical probability of rolling a 1 is 1/6.   perhaps you got really lucky and never rolled a 1   in those 60 times.   your experimental probability is 0.   or perhaps you rolled a 1   20 times.   your experimental probability is 20/60 is 1/3.     it really just depends on how you rolled in that experiment.

2.   never

the probability of the event occurring is 1.   that is being 100 % sure it will happen.   that is the maximum amount of confidence we have.

3.   no customer card cost:   .08 times number of pages

customer card cost:   7.50 + .05 times number of pages

we want to find when it costs the same amount, so we will set these equal

let c = number of pages

.08c = 7.50+.05c

subtract .05c from each side

.08c-.05c = 7.5+.05c-.05c

.03c=7.5

divide each side by .03

.03c/.03 = 7.5/03

c =250  

the cost is the same at 250 pages