slope intercept word problem

[Dillinger4]

What would be the waiting time if four clerks are working?

x(Number of clerks working) 6,8
y(Number of minutes wating time) 8,5

We have to points or ordered pairs (6,8)(8,5)

Before i use the slope intercept form i have to get the slope using the point slope form. y₂ - y₁ / x₂ - x₁ = m which ends up being -3/2.

Now when i plug the values in the slope intercept form y = mx + b. 8 = -3/2(6) + b --> 8 = -9 + b and solve for b. b = 17. Now it would be logically correct that the less clerks that work the more waiting time there will be. But is 17 minutes the right answer?

[jemidiah]

All of your arithmetic is perfect, you just need to continue to the final step: plugging in 4 (the number of waiters) for x in the equation you derived (y = -3x/2 + 17), so:

y = -3(4)/2 + 17 = -12/2 + 17 = -6 + 17 = 11 minutes waiting time.

[Dillinger4]

Ah fantastic! Thanks for the help.