# Work Efficiency

• Jun 4th 2009, 11:28 AM
lisa1984wilson
Work Efficiency
I have a work efficiency problem with the function Q(t)=-t^3+6t^2+15t

It wants me to find the time when the workers are most efficient and least efficient between 8:00 a.m. and 12:00 noon.

I got x=-1 and x=5 from first derivative now do I have to plug these numbers in to derivatives 1 through 4 to find efficiency.
• Jun 4th 2009, 11:34 AM
skeeter
Quote:

Originally Posted by lisa1984wilson
I have a work efficiency problem with the function Q(t)=-t^3+6t^2+15t

It wants me to find the time when the workers are most efficient and least efficient between 8:00 a.m. and 12:00 noon.

I got x=-1 and x=5 from first derivative now do I have to plug these numbers in to derivatives 1 through 4 to find efficiency.

what does Q(t) represent?
• Jun 4th 2009, 11:37 AM
lisa1984wilson
• Jun 4th 2009, 11:52 AM
skeeter
efficiency is measured by the rate that the radios are produced.

you want to find where Q'(t) is a maximum (most efficient) and a minimum (least efficient).

the domain for t should be 0 to 4, 0 corresponding to 8:00 and 4 corresponding to 12:00
• Jun 5th 2009, 06:35 AM
lisa1984wilson
I'm still not sure how to calculate this...I got the critical points x=-1 and x=5 what do I have to do next to figure this out..thanks!
• Jun 5th 2009, 06:54 AM
skeeter
Quote:

Originally Posted by lisa1984wilson
I'm still not sure how to calculate this...I got the critical points x=-1 and x=5 what do I have to do next to figure this out..thanks!

once again ... you want to find the extrema for Q'(t), not Q(t).