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agasfer [191]
3 years ago
6

Một ủy ban an toàn kiểm tra ngẫu nhiên 900 công nhân xây dựng trong thời gian làm việc, thấy có 48 công nhân không mang mũ bảo h

ộ. Hãy ước lượng tỷ lệ công nhân không mang mai bảo hộ trong thời gian làm việc với độ tin cậy 98%
Mathematics
1 answer:
Usimov [2.4K]3 years ago
6 0

Answer:

The percentage of workers not wearing the helmets is 5.3 %.

Step-by-step explanation:

A safety committee randomly examined 900 construction workers during their work, and found that 48 workers were not wearing helmets. Estimate the percentage of workers who do not wear protective masks during their working time with 98% confidence

total workers = 900

Not wearing helmet = 48

Percentage which are not wearing the helmets

= \frac{48}{900}\times 100 = 5.3 %%

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Find the surface are of the cylinder in terms of pi
Andrej [43]
Hello!

To find the surface area of a cylinder you use the equation

SA = 2 \pi rh + 2 \pi  r^{2}

SA is surface area
r is radius
h is height

PUt in the values you know

SA = 2 \pi (7)(18) + 2 \pi  * 7^{2}

Square the number

SA = 2 \pi (7)(18) + 2 \pi * 49

Multiply 7 and 18

SA = 2 \pi * 126 + 2 \pi  * 49

Multiply 126 by 2

SA = 252 \pi  + 2 \pi  * 49

Multiply the 49 by 2

SA = 252 \pi  + 98 \pi

Add

SA = 350 \pi

The answer is A)350 \pi cm^{2}

Hope this helps!
7 0
3 years ago
At 7:00 A.M., Alicia pours a cup of tea whose temperature is 200°F. The tea starts to cool to room temperature (72°F). At 7:02 A
alexgriva [62]

Answer: A) Option B

B) 22.3 minutes.

Step-by-step explanation:

The temperature decreases in an exponential decrease, this means that we can write the equation as:

T(x) = A*r^x + B

Where A is the difference between the initial temperature and the room temperature, B is the room temperature, and r is a positive number smaller than 1, that says "how fast" the temperature decreases (and x is the variable, in units of time)

We know that the initial temperature

A = 200° - 72° = 128°

B = 72°

T(x) = 128°r^x + 72°

The only option with those two values is option B.

T(x) =  128(0.989)^x + 72

We should check that when x = 2m, the temperature must be 197°

T(2m) = 128*(0.989)^2 + 72 = 197.2° (that we can round down to 197°)

So this equation is correct

Now we want to find the time such the temperature is 172°F

then:

172° = 128°(0.989)^x + 72°

100° = 128°(0.989)^x

100/128 = (0.989)^x

x = ln(100/128)/ln(0.989) = 22.3 minutes.

Let's check in our equation:

T(22.3) =  128°(0.989)^22.3 + 72 = 172°

8 0
3 years ago
PLEASE HELP WILL GIVE BRAINLY<br><br>(USE BAR NOTATION IF NEEDED!!!!!!<br>CONVERT TO DECIMAL
emmainna [20.7K]

Answer:

3.34 is the decimal form but the question is unclear, what is it that you need?

Step-by-step explanation:

5 0
3 years ago
Read 2 more answers
Please help!
laila [671]
Because
\frac{f(x)}{x-3} = 2x^{2} + 10x - 1
therefore
f(x) = (x-3)(2x² + 10x - 1) + k, where k =  constant.

Because f(3) = 4, therefore k =4.
The polynomial is
f(x) = 2x³ + 10x² - x - 6x² - 30x + 3 + 4
      = 2x³ + 4x² - 31x + 7

Answer:  f(x) = 2x³ + 4x² - 31x + 7

6 0
3 years ago
Lin runs 5 laps around a track in 8 minutes.
andrezito [222]

Answer:

To run one lap Lin takes 1.6 minutes.

Step-by-step explanation:

To find this answer you would do 8 divided by 5. Always remember when dividing time goes first unless the instructions / directions / your teacher says differently. So, when you do 8 divided by 5 the answer you get is 1.6, and there is your answer. Also to check your answer you can do 1.6 times 5, and you get 8, so you know that 1.6 is the correct answer.

5 0
3 years ago
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