The number n of people using the elevator in an office building every hour is given by n = t2 − 10t + 40. in this equation, t is the number of hours after the building opens in the morning, 0 ≤ t ≤ 12. will the number of people using the elevator ever be less than 15 in any one hour? use the discriminant to answer.

The number of persons using the elevator at any hour is never going to be less that 15.

Step-by-step explanation:

To solves this you have to suppose that there are at least 15 persons on the elevator, and the equation is converted into an inequation:  

Now you transform the inequation back to an equation to solve it:

You need to know if there is any negative solution for the equation, to do this you can use the discriminant for a quadratic equation:

In this case, you have a=1, b=-10, c=25

Since the discriminant is 0 and a<0 the equation always is going to be positive. Therefore, the number of persons using the elevator at any hour is never going to be less than 15.

b.) 160 miles on a 5 gallons car

step-by-step explanation:

240/10=24 miles/gallon

160/5=32 miles/gallon

30/1=30 miles/gallon

168/6= 28 miles/gallon

32 miles/gallon is the most amount, so this is the best.

answer: a. 13/44

step-by-step explanation: judging by the information given to us, we are looking for experimental probability. we can see that 13 males have chosen chocolate ice cream. there are 44 ice creams in total (remember that the total is always the denominator). so our answer is 13/44.