But then you could divide by, you're dividing I'm assuming by time right over here. So this is times minutes divided by minutes. So then you just get degrees Celsius again. So this expression right over here is just the average temperature over those 10 minutes. Then they say use a trapezoidal sum with the 4 subintervals indicated by the table to estimate this. So a trapezoidal sum is, we don't know the exact function here so we won't be able to analytically evaluate this definite integral. But what we can do is divide this area into 4 sections.