Estimation Rita goes to the mall. If x is the number of items she bought, the expression 18.54x+23 gives the amount she spent in dollars at one store. Then she spent 25 dollars at another store. Find the expression which represents the amount Rita spent at the mall. Then estimate how much Rita spent if she bought 2 items.

Step-by-step explanation:

The total amount Rita spent is ...

  (18.54x +23) +(25) = 18.54x +48 . . . total spent

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When x=2, that is approximately ...

  (18.5)(2) + 48 = 37 +48 = (40 -3) +(50 -2) = (40 +50) -(3 +2) = 90 -5 = 85

Rita spent about $85 if she bought 2 items.

Additional comment

Estimation is often done using 1 significant figure. In this case, that would mean rounding the equation to 20x+50, so it would give a value of 90 when x=2.

An additional task when estimating is to estimate the error in the estimate. Here, using 20x+50 has an error of approximately 1.5x+2 (too high), so the error for 2 items will be about (1.5(2)+2) = 5. That is, the estimate of 90 is approximately 5 too high. Even this estimate has a remaining small error of 0.04x (too low).

3.4 pizzas

step-by-step explanation:

given is a scatter plot showing number of pizzas sold during weeks for different issues of coupon

y represents number of pizzas sold and x number of coupons issued

y is marked verticaly and x horizontally

the trend line is given as

y =3.4x+43

this says that even when no coupon is issued pizzas sold will be 43

and rate of change of pizza sold for 1 unit of coupon = slope = 3.4

i.e. when x increases by 1 unit y increases by 3.4 units

hence for each additional coupon issued 3.4 pizzas more will be sold

ou would have 12 of each