Answer:
a) 
b) 
c) 
d) 
Step-by-step explanation:
Assuming the following questions:
a. Between 20 and 25 gallons
Let X the random variable that represent the sports drink consumption of a population, and for this case we know the distribution for X is given by:
Where
and
We are interested on this probability
And the best way to solve this problem is using the normal standard distribution and the z score given by:
And if we find the z score for each limit we got:


And we can use the normal standard distirbution table and we got:

b. Less than 19 gallons

And using the normal table we got:

c. More than 21 gallons

And using the normal table and the complement rule we got:

d. Between 26 and 28 gallons

![z = \frac{28-20}{3}=2.67/tex]And we can use the normal standard distirbution table and we got:[tex] P(2](https://tex.z-dn.net/?f=%20z%20%3D%20%5Cfrac%7B28-20%7D%7B3%7D%3D2.67%2Ftex%5D%3C%2Fp%3E%3Cp%3EAnd%20we%20can%20use%20the%20normal%20standard%20distirbution%20table%20and%20we%20got%3A%3C%2Fp%3E%3Cp%3E%5Btex%5D%20P%282%3Cz%3C2.67%29%3D%20P%28z%3C2.67%29%20-P%28Z%3C2%29%20%3D%200.996%20-0.977%3D0.019)