Tips a pizza delivery driver, always trying to increase tips, runs an experiment on his next 40 deliveries. he flips a coin to decide whether or not to call a customer from his mobile phone when he is five minutes away, hoping this slight bump in customer service will lead to a slight bump in tips. after 40 deliveries, he will compare the average tip percentage between the customers he called and those he did not. 1. was the experiment randomized and replicated? 2. is this experiment blinded? 3. what are the experimental units and how did he randomize treatments?

ab will be equal to

see explanation

step-by-step explanation:

a

(6r + 7) + (13 + 7r) ( remove brackets and collect like terms )

= 6r + 7 + 13 + 7r

= 13r + 20

b

remove brackets and collect like terms

13 - r - 1 + r

= 12 - r

c

remove brackets and collect like terms

= - 8 - r + 2r - 4

= - 12 + r

d

remove brackets and collect like terms

= 7r - - - 6r

[-   - = - - = - ]

= r -

you could deduce the conclusion directly using the facts pertaining to the specific situation.

hope this .

this is a direct variation proportion. y = kx

y is the total amount due, k is the constant of variation, and x is the number of texts sent.

plug in the 3.20 and the 16 to solve for the "k". this is the constant of proportionality. it is the value that will not change.

3.20 = k(16). solving you get $.20 per text.

the equation would then be y = .20x