calculus (gr 12)
posted by Maria .
the productivity of a person at work (on a scale of 010) is modeled by a cosine function: 5cos (pie/2t) +5, where t is in hours. If the person starts work at t=0, being 8:00 am, at what times is the worker the least productive?
a) 12pm
B) 10 am and 2pm
C) 11 am and 3 pm
D) 10 am,12pm and 2 pm
MULTIPLE CHOICE

cos has max at t=0
cos(pi/2 t) has period 4
cos has min at 1/2 the period.
so,
f(0) (8am) = 5*1+5 = 10
f(1) (9am) = 5*0+5 = 5
f(2) (10am) = 5*(1) + 5 = 0
...
least productive at 10:00,14:00,...
(B)