The price of a company's stock

Question

the price of a companys stock on a particular day is modeled by the equation y=-.5x^2 + 2x + 40, y is price of stock in dollars, x is the number of hours after the start of the business day

select the true statements:

a) Stock had an initial price of $40 at the start of the day

b) Stock had an initial price of $40, 8 hours after start of the day 

c) stock had a final price of $24, 8 hours after start of the day

d) stock had a minimum of $34, 2 hours after start of the day

e) stock had maximum of $42, 2 hours after start of the day 

Answer 1

You should be able to select the correct statement(s) by making an x-y table that contains x = 0, 2 and 8.

 

The choices are (a), (c), and (e)

Answer 2

a is true. (x = 0 at the start of the day which makes y = 40)

c is also true. Plug 8 in for x:  y = -.5(64)+2(8)+40 = -32+16+40 = 24

     at 2 hours:

     y = -.5(4) + 4 + 40 = 44-2 = 42.

so e is also true;

 

a, c, and e are true