In the sequence: 87, 72, 66, 51, 45, ..., what number should come next? a) 39
b) 30
c) 31
d) 36

B) 30

Step-by-step explanation:

The difference between 87 and 72 is 15, the difference between 72 and 66 is 6, the difference between 66 and 51 jumps back to 15 again and the difference between 51 and 45 jumps to 6 again. This shows that the difference between the numbers are first 15,then 6 then 15 then 6...and so on. Since tue latest difference is 6, the next difference between 45 and the next number would be 15.

Let the number be x.

45-x = 15

45 = 15+x

Isolate the x.

45-15 = x

Find x.

x = 30

Thus, the next number is 30.

lo.lll

step-by-step explanation:

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