Using the vertex of the quadratic function, it is found that:
a) The maximum number of customers in the store is at 12 P.M.
b) 75 customers are in the store at this time.
The number of customers in x hours after 7 AM is given by:

Which is a quadratic equation with coefficients 
Item a:
The maximum value, considering that a < 0, happens at:

Hence:

5 hours after 7 A.M, hence, the maximum number of customers in the store is at 12 P.M.
Item b:
The value is y(5), hence:

75 customers are in the store at this time.
A similar problem is given at brainly.com/question/24713268
The distance is 14 between coordinates'
Answer:
100.7%
Step-by-step explanation:
Since the interest is compounded quarterly, and there are 4 quarters per year, that would leave us with 32 quarters total where interest is acquired. Now, we need to find the interest rate, that would be required in order to end up with 420 dollars after 32 quarters.
We can setup a formula using our period of time and the money he invested into the bank:

We can divide 340 from both sides, and simplify the right side to 21 divided by 17:

Taking the 32th root of 21/17 is equal to 1.00662, which is equal to 100.0662%. To the nearest tenth of a percent, this is equal to 100.7%.
(28 : 100) *6 = 1.68 (tax)
28 + 1.68 = 29.68 (total cost)