[shannabee]

Last two Questions Pleaese help:

A survey of video game stores indicated that a price of $75 each, the deman would be 4 thousand games, at a price of $35 each, the demand would be 14 thousand games. If a linear relationship between price and demand exists, which of the following equations models the price demand relationship. Let y represent price per video game and x represent the demand in thousands.
y=4x
y=-4x+83
y=2x+63
y=-4x+91

Leanne leaves town traveling at an average speed of 46mph. Afetr 3 hours , Bart leaves town traveling in the same direction at an average of 66 mph. which of the following equations could be used to represent the distance between Leanne and Bart after x hours. Let x represent time in hours that Bart have been traveling and y represent the distance between Leanne and Bart.
y=138+20x
y=138-6x
y=20x
y-138-20x

[sarnian]

Hello shannabee

Question 1

A survey of video game stores indicated that a price of $75 each, the deman would be 4 thousand games, at a price of $35 each, the demand would be 14 thousand games. If a linear relationship between price and demand exists, which of the following equations models the price demand relationship. Let y represent price per video game and x represent the demand in thousands.
y = 4x
y = -4x + 83
y = 2x + 63
y = -4x + 91

Between the limits y=75 , x=4 and y=35 , x=14 the price/sales relation is linear.
Which means that both sets of values for x and y should be valid in one of the provided equations.

Let's do 2 answers, you do the other 2 :

Note : if either option is wrong, the answer is wrong.

y=4x : y=75 x=4 ---> 4x=16 But 75 is not 16. Wrong.
y=4x : y=35 x=14 --> 4x=56 But 56 is not 35. Wrong also.
So this answer is wrong.

y=-4x+83 : y=75 x=4 ---> -4x+83 = -16 + 83 = 67. But 67 is not 75. Wrong!
y=-4x+83 : y=35 x=14 --> -4x+83 = -56 + 83 = 27. But 27 is not 35. Wrong also!
So this answer is wrong.

Now do the next two equations yourself and find out which one is correct !

Question 2

Leanne leaves town traveling at an average speed of 46mph. Afetr 3 hours , Bart leaves town traveling in the same direction at an average of 66 mph. which of the following equations could be used to represent the distance between Leanne and Bart after x hours. Let x represent time in hours that Bart have been traveling and y represent the distance between Leanne and Bart.
y = 138 + 20x
y = 138 - 6x
y = 20x
y = 138 - 20x

x is time in hours for Bart (B)
y is distance between Bart and Leanne (B and L)

Note 1 : L travelled at x=0 already 3 x 46 mph = 138 mph.
Note 2 : Every more hour L travels this increases with 46 mph.
Note 3 : B travelled at x=0 nil mph.
Note 4 : Every more hour B travels this increases with 66 mph.

So the distance y between L and B = (138 mph + x times 46 mph) - x times 66 mph.
Abbreviated this becomes y = (138 + 46x) - 66x.

Again let's do 2 answers, you do the other 2 :

y = 138 + 20x. Also y = (138 + 46x) - 66x.
138 + 20x = (138 + 46x) - 66x.
138 + 20x + 66x = 138 + 46x
20x = 138x. Wrong equation!

y = 138 - 6x. Also y = (138 + 46x) - 66x.
138 - 6x = (138 + 46x) - 66x.
138 - 6x = 66x = 138 + 46x
6x = 46 x. Wrong equation also!

Now do the next two equations yourself and find out which one is correct !