Starting at home, Jessica traveled uphill to the grocery store for 18 minutes at just 20 mph. She then traveled back home along the same path downhill at a speed of 60 mph. What is her average speed for the entire trip from home to the grocery store and back?

It takes 45 minutes for 4 people to paint 5 walls. How many minutes does it take 6 people to paint 4 walls?

It takes 52 minutes for 5 people to paint 5 walls. How many minutes does it take 20 people to paint 20 walls?

It takes 48 minutes for 7 people to paint 7 walls. How many minutes does it take 20 people to paint 20 walls?

Try this solution with short explanation; note, the suggested way is not the shortest one; the answers are marked with red colour.

Task no. 2: another solution is 45* (4/5) / (6/4) = 24 min.

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