From the given the function, <span>y(t)=−t²+14t−40; the graph will be as shown below: From the graph, it is evident that between the intervals 6</span>≤t≤8<span>: The value of our function decreases over the given interval. Hence the answer is: </span><span>a. The value of y(t) increases over the interval 6≤t≤7 </span>