Answer:
X = {0, 1, 2, 3, 4}
Step-by-step explanation:
If X is the number of nonzero digits in a 4-digit PIN with no restriction on the digits, the pin can have up to 4 nonzero digits.
Let's see some examples:
If the PIN is 0000 then X = 4
If the PIN is 2045 then X = 3
If the PIN is 7546 then X = 0
From the previous examples, we can see that the possible values for X are 0, 1, 2, 3, 4.
Thus X = {0, 1, 2, 3, 4}
Answer:
18 people ordered beer.
Step-by-step explanation:
15 + 3 = 18 people
Let x be the shorter side, and y be the longer side
There would be 4 fences along the shorter side, and 2 fences along the longer side
4x + 2y = 800
Rewrite in terms of y:
y = 400 − 2x
The area of the rectangular field is
A = x*y
Replace Y with the equation above:
A = x(400 − 2x)
A = − 2x^2 + 400x
The area is a parabola that opens downward, the maximum area would occur at the parabola vertex.
At the vertex
x = −b/2a
= −400/[2(−2)]
= 100
y = 400 −2x
y = 400 -2(100)
y = 400-200
y = 200
The dimension of the rectangular field that maximize the enclosed area is 100 ft x 200 ft.
