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sergij07 [2.7K]
3 years ago
11

The difference between a number x and 13 is 21

Mathematics
1 answer:
Setler [38]3 years ago
3 0

Answer:

x = 34

Step-by-step explanation:

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PLZ help me with this question
olga2289 [7]

Answer:

3

Step-by-step explanation:

3x4=12

its 3 because you need to find the balances so when you have 3 and you multiped my 4 you get 12 same as the other square.

3 0
2 years ago
It is assumed that the test results for a class follow a normal distribution with a mean of 78 and a standard deviation of 36. I
HACTEHA [7]

Answer:

0.7143

- You know the minimum possible grade of the student

- You want to find out the probability that that grade which is greater than 72 is also greater than 84

- Expect the answer to be 0.7143

- The explanation/steps is given below

- The answer seems (and is) reasonable. You only created a new lower limit.

Step-by-step explanation:

Distribution Type: Normal

Mean: 78

Standard deviation: 36

Range of marks: [78 - 36], [78 + 36]  = [42 to 114]

If you know that a student's grade is greater than 72, what is the probability that it's greater than 84?

In this case, the full probability level is between 72 and the upper limit of 114 (instead of between 42 and 114). First, find the fraction of this probability.

[114 - 72] ÷ [114 - 42]  = 42/72  = 0.5833

So, the probability of a student's mark falling between 72 and 114 is 0.5833.

Now making this a whole interval, 114 - 72 = 42

What fraction of this interval of 42 will bear marks between 84 and 114?

[114 - 84]  = 30

30/42  = 0.7143

Because of the first part of the question "If you know (are sure) that a student's grade is greater than 72...", your answer stops at 0.7143, since 72 was used as the lower limit.

8 0
2 years ago
The radioactive substance polonium-210, with a half-life of 138.39 days, is present in tobacco. Suppose that the soot in an ex-s
Ksju [112]

Answer:

16.07 milligrams

Step-by-step explanation:

From the question,

Using the formula of radioactive decay,

R/R' = 2ᵃ/ᵇ..................... Equation 1

Where R = Original mass of the polonium-210, R' = Final mass of polonium-210 after decaying, a = Total disintegration time, b = half life of polonium-210.

Make R' the subject of the equation

R' = R/(2ᵃ/ᵇ)................ Equation 2

Given: R = 100 milligrams, a = 1 years = 365 days, b = 138.39 days

Substitute these values into equation 2

R' = 100/(2³⁶⁵⁰⁰/¹³⁸³⁹)

R' = 100/(6.222)

R' = 16.07 milligrams of plonium-210

3 0
2 years ago
How to write 7+2-3-8 in sigma notation
Valentin [98]
(7+2-3-8)=0
N=7
Brainliest pts
Hope this helps
7 0
3 years ago
Does anyone knows the answers to these
jarptica [38.1K]
Median is 17
Range is 17.4
IQR is 6
5 0
2 years ago
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