I need help with 6 and 7 who ever answer the fastice and the right answer will get brainiest

Ricardo ran the 400 meter race 3 times his fastest time was 54.3 seconds his slowest time was 56.1 seconds if his average time was 55.0 seconds what was his time for the third race

How many zeros does the function f(x)=4x3-x2+1 have

Use composition to determine if (x) or h(x) is the inverse of f(x) for the limited domain x2-1.