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3 years ago

Need help on the last problem please.

Mathematics

1 answer:

pshichka [43]3 years ago

6 0

Answer:

6 of x and 5 of y

Step-by-step explanation:

x = number of closets of the first type

y = number of closets of the second type

1200 = 100x + 120y

100 = 10x + 8y

10x = 100 - 8y

10x(100 - 8y) + 120y = 1200

1000 - 80y + 120y = 1200

40y = 200

y = 5

100 = 10x + 8×5 = 10x + 40

60 = 10x

x = 6

20x + 24y = max

20×6 + 24×5 = 120 + 120 = 240

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A rectangular tank that is 2048 ft cubed with a square base and open top is to be constructed of sheet steel of a given thicknes

ira [324]

Answer:

The box should have base 16ft by 16ft and height 8ft Therefore,dimensions are 16 ft by 16 ft by 8 ft

Step-by-step explanation:

We were given the volume of the tank as, 2048 cubic feet.

Form minimum weight, the surface area must be minimum.

Let the height be h and the lengths be x

the volume will be: V=x²h then substitute the value of volume, we have

2048=hx²

hence

h=2048/x²

Since the amount of material used is directly proportional to the surface area, then the material needs to be minimized by minimizing the surface area.

The surface area of the box described is

A=x²+4xh

Then substitute h into the Area equation we have

A= x² + 4x(2048/x²)

A= x² + 8192/x

We want to minimize

dA/dx = -8192/x² + 2 x= 0 for max or min

when dA/dx=0

dA/dx= 2x-8192/x²=0

2x=8192/x²

Hence

2x³=8192

x³=4096

x=₃√(4096)

X=16ft

Then h=2048/x²

h=2048/16²

h=8ft

The box should have base 16ft by 16ft and height 8ft

Hence the dimensions are 16 ft by 16 ft by 8 ft

8 0

3 years ago

Among 18 students in a room, 7 study mathematics, 10 study science, and 10 study computer programming. Also, 3 study mathematics

tatyana61 [14]

Answer:

2 students study none of the subjects.

Step-by-step explanation:

Consider the attached venn diagram. First, we place that 1 student studies the three subjects. Then, we notice that 3 students study math and science, then 2 students study math and science only, since we have 1 that studies the three subjects. In the same fashion, we have that 3 students study Math and computer programming only (since they are 4 in total). Note that since 7 students study math, and we already have 6 students in our count in the math subject this implies that 1 student studies only math (the total number of students inside the math circle must add to 7).

We also have that 4 students study science and computer programming only. Which implies that we must have 3 students that study science only (10 students that study science in total) and 2 students study computer programming (for a total of 10 students). The total number of students that study none is the total number of students (18) minus the amount of students that is inside the circles (16) which is 2.