Question

Brendon is walking home from a place that is 1.5 miles away. The function y = 7,920 − 270x represents Brendon’s distance in feet from home, y, in relation to the number of minutes he walks, x. Bryan is also walking home. Every 15 minutes, he writes down the number of feet left to reach home, as shown in the table.

Minutes
Feet
0
8,000
15
3,800

Which statements about this situation are true?
Brendon walks faster.
Bryan walks faster.
Brendon and Bryan walk at the same speed.
Brendon was farther away from home when he started walking.
Bryan was farther away from home when he started walking.
Brendon and Bryan were an equal distance from home when they started walking.

Answer 1

Answer:

Bryan walks faster

Bryan was farther away from home when he started walking.

Explanation:

Given the following :

Brendon's distance in feet from home 'y' in relation to the number of minutes walked 'x'

y = 7,920 − 270x

For bryan:

Minutes (x) - - - 0 - - - - - 15

Feet ( y) - - 8000 - - - 3800

General form of a linear equation :

y = mx + C

m = gradient / slope

m = (y2 - y1) / (x2 - x1)

m = (3800 - 8000) / (15 - 0)

m = -4200 / 15 = - 280

Intercept 'c' = 8000 (where line intersect the y axis), (since y = 8000, when x = 0)

Therefore,

Bryan's model:

y = 8000 - 280x

Comparing both functions :

Bryan has a greater speed ( from the gradient)

Bryan was farther away from home when he started walking ( intercept )

Explanation:

Answer 2

Bryan walks faster

Bryan was farther away from home when he started walking.

Explanation:

Given the following :

Brendon's distance in feet from home 'y' in relation to the number of minutes walked 'x'

y = 7,920 − 270x

For bryan:

Minutes (x) - - - 0 - - - - - 15

Feet ( y) - - 8000 - - - 3800

General form of a linear equation :

y = mx + C

m = gradient / slope

m = (y2 - y1) / (x2 - x1)

m = (3800 - 8000) / (15 - 0)

m = -4200 / 15 = - 280

Intercept 'c' = 8000 (where line intersect the y axis), (since y = 8000, when x = 0)

Therefore,

Bryan's model:

y = 8000 - 280x

Comparing both functions :

Bryan has a greater speed ( from the gradient)

Bryan was farther away from home when he started walking ( intercept )