The time required for an automotive center to complete an oil change service on an automobile approximately follows a normaldistribution, with a mean of 1717 minutes and a standard deviation of 2.52.5 minutes. (a) The automotive center guarantees customers that the service will take no longer than 2020 minutes. If it does take longer, the customer will receive the service forhalf-price. What percent of customers receive the service forhalf-price?
(b) If the automotive center does not want to give the discount to more than 33% of its customers, how long should it make the guaranteed time limit?

A relation f(x) is a function only when there is not two different values in the range that are related to the same value in the domain.

This means that does not exist y1 and y2 such:

f(x1) = y1

f(x1) = y2

if this happens, f is not a function.

Upper graphs, from left to right.

the first graph is a constant line, this is a function f(x) = c.

The second graph is not a function.

The third graph is not a function

the fourth graph is a function

the fourth graph is a function

the fifth graph is not a function.

From the lower ones:

The set of data can be a function

y = 2x^2 - 3 is a function.

The diagram with two circles is not a function (there are more than one output for some imputs)

The last table is a function