2. which of the following variables are discrete, and which are continuous? explain your answers.
number of items purchased by a customer at a grocery store
time required to solve a puzzle
length of a piece of lumber
number out of 10 customers who pay with a credit card

Discrete: Number of items purchased by a customer at a grocery store. Number out of 10 customers who pay with a  credit card.

Continuous: Time required to solve a puzzle; Length of a piece of lumber.

Step-by-step explanation:

Consider the provided information.

A discrete variable is a variable whose value is obtained by counting and they can be described by an integer value.

A continuous variable is a variable whose value is obtained by measuring.

Thus, discrete variables are:

The number of items purchased by a customer at a grocery store.

Number out of 10 customers who pay with a credit card

Continuous variables are:

Time required to solve a puzzle.

Length of a piece of lumber.

-2

7 - 9 = -2

reversed:

-2 + 9 = 7

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204